(window.webpackJsonp=window.webpackJsonp||[]).push([[1817],{2425:function(t,e,a){"use strict";a.r(e);var s=a(71),r=Object(s.a)({},(function(){var t=this,e=t.$createElement,a=t._self._c||e;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"dml-数据操作语言"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#dml-数据操作语言"}},[t._v("#")]),t._v(" DML (数据操作语言)")]),t._v(" "),a("h2",{attrs:{id:"数据接入"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#数据接入"}},[t._v("#")]),t._v(" 数据接入")]),t._v(" "),a("p",[t._v("IoTDB为用户提供多种插入实时数据的方式，例如在"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Client/Command Line Interface.html"}},[t._v("Cli/Shell工具")]),t._v("中直接输入插入数据的INSERT语句，或使用Java API（标准"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Client/Programming - JDBC.html"}},[t._v("Java JDBC")]),t._v("接口）单条或批量执行插入数据的INSERT语句。")],1),t._v(" "),a("p",[t._v("本节主要为您介绍实时数据接入的INSERT语句在场景中的实际使用示例，有关INSERT SQL语句的详细语法请参见本文"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Operation Manual/SQL Reference.html"}},[t._v("INSERT语句")]),t._v("节。")],1),t._v(" "),a("h3",{attrs:{id:"使用insert语句"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#使用insert语句"}},[t._v("#")]),t._v(" 使用INSERT语句")]),t._v(" "),a("p",[t._v("使用INSERT语句可以向指定的已经创建的一条或多条时间序列中插入数据。对于每一条数据，均由一个时间戳类型的时间戳和一个数值或布尔值、字符串类型的传感器采集值组成。")]),t._v(" "),a("p",[t._v("在本节的场景实例下，以其中的两个时间序列"),a("code",[t._v("root.ln.wf02.wt02.status")]),t._v("和"),a("code",[t._v("root.ln.wf02.wt02.hardware")]),t._v("为例 ，它们的数据类型分别为BOOLEAN和TEXT。")]),t._v(" "),a("p",[t._v("单列数据插入示例代码如下：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v('IoTDB > insert into root.ln.wf02.wt02(timestamp,status) values(1,true)\nIoTDB > insert into root.ln.wf02.wt02(timestamp,hardware) values(1, "v1")\n')])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("以上示例代码将长整型的timestamp以及值为true的数据插入到时间序列"),a("code",[t._v("root.ln.wf02.wt02.status")]),t._v("中和将长整型的timestamp以及值为”v1”的数据插入到时间序列"),a("code",[t._v("root.ln.wf02.wt02.hardware")]),t._v("中。执行成功后会返回执行时间，代表数据插入已完成。")]),t._v(" "),a("blockquote",[a("p",[t._v("注意：在IoTDB中，TEXT类型的数据单双引号都可以来表示,上面的插入语句是用的是双引号表示TEXT类型数据，下面的示例将使用单引号表示TEXT类型数据。")])]),t._v(" "),a("p",[t._v("INSERT语句还可以支持在同一个时间点下多列数据的插入，同时向2时间点插入上述两个时间序列的值，多列数据插入示例代码如下：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("IoTDB > insert into root.ln.wf02.wt02(timestamp, status, hardware) VALUES (2, false, 'v2')\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("插入数据后我们可以使用SELECT语句简单查询已插入的数据。")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("IoTDB > select * from root.ln.wf02 where time < 3\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("结果如图所示。由查询结果可以看出，单列、多列数据的插入操作正确执行。\n"),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51605021-c2ee1500-1f48-11e9-8f6b-ba9b48875a41.png"}})])],1),t._v(" "),a("h3",{attrs:{id:"insert语句的错误处理"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#insert语句的错误处理"}},[t._v("#")]),t._v(" INSERT语句的错误处理")]),t._v(" "),a("p",[t._v("若用户向一个不存在的时间序列中插入数据，例如执行以下命令：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v('IoTDB > insert into root.ln.wf02.wt02(timestamp, temperature) values(1,"v1")\n')])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("由于"),a("code",[t._v("root.ln.wf02.wt02. temperature")]),t._v("时间序列不存在，系统将会返回以下ERROR告知该Timeseries路径不存在：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("Msg: The resultDataType or encoding or compression of the last node temperature is conflicting in the storage group root.ln\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("若用户插入的数据类型与该Timeseries对应的数据类型不一致，例如执行以下命令：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("IoTDB > insert into root.ln.wf02.wt02(timestamp,hardware) values(1,100)\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("系统将会返回以下ERROR告知数据类型有误：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("error: The TEXT data type should be covered by \" or '\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("h2",{attrs:{id:"数据查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#数据查询"}},[t._v("#")]),t._v(" 数据查询")]),t._v(" "),a("h3",{attrs:{id:"时间切片查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#时间切片查询"}},[t._v("#")]),t._v(" 时间切片查询")]),t._v(" "),a("p",[t._v("本节主要介绍时间切片查询的相关示例，主要使用的是"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Operation Manual/SQL Reference.html"}},[t._v("IoTDB SELECT语句")]),t._v("。同时，您也可以使用"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Client/Programming - JDBC.html"}},[t._v("Java JDBC")]),t._v("标准接口来执行相关的查询语句。")],1),t._v(" "),a("h4",{attrs:{id:"根据一个时间区间选择一列数据"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#根据一个时间区间选择一列数据"}},[t._v("#")]),t._v(" 根据一个时间区间选择一列数据")]),t._v(" "),a("p",[t._v("SQL语句为：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select temperature from root.ln.wf01.wt01 where time < 2017-11-01T00:08:00.000\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("其含义为：")]),t._v(" "),a("p",[t._v("被选择的设备为ln集团wf01子站wt01设备；被选择的时间序列为温度传感器（temperature）；该语句要求选择出该设备在“2017-11-01T00:08:00.000”（此处可以使用多种时间格式，详情可参看"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Concept/Data Model and Terminology.html"}},[t._v("2.1节")]),t._v("）时间点以前的所有温度传感器的值。")],1),t._v(" "),a("p",[t._v("该SQL语句的执行结果如下：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/23614968/61280074-da1c0a00-a7e9-11e9-8eb8-3809428043a8.png"}})]),t._v(" "),a("h4",{attrs:{id:"根据一个时间区间选择多列数据"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#根据一个时间区间选择多列数据"}},[t._v("#")]),t._v(" 根据一个时间区间选择多列数据")]),t._v(" "),a("p",[t._v("SQL语句为：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status, temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("其含义为：")]),t._v(" "),a("p",[t._v("被选择的设备为ln集团wf01子站wt01设备；被选择的时间序列为供电状态（status）和温度传感器（temperature）；该语句要求选择出“2017-11-01T00:05:00.000”至“2017-11-01T00:12:00.000”之间的所选时间序列的值。")]),t._v(" "),a("p",[t._v("该SQL语句的执行结果如下：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/23614968/61280328-40a12800-a7ea-11e9-85b9-3b8db67673a3.png"}})]),t._v(" "),a("h4",{attrs:{id:"按照多个时间区间选择同一设备的多列数据"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#按照多个时间区间选择同一设备的多列数据"}},[t._v("#")]),t._v(" 按照多个时间区间选择同一设备的多列数据")]),t._v(" "),a("p",[t._v("IoTDB支持在一次查询中指定多个时间区间条件，用户可以根据需求随意组合时间区间条件。例如，")]),t._v(" "),a("p",[t._v("SQL语句为：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where (time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000) or (time >= 2017-11-01T16:35:00.000 and time <= 2017-11-01T16:37:00.000);\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("其含义为：")]),t._v(" "),a("p",[t._v("被选择的设备为ln集团wf01子站wt01设备；被选择的时间序列为“供电状态（status）”和“温度传感器（temperature）”；该语句指定了两个不同的时间区间，分别为“2017-11-01T00:05:00.000至2017-11-01T00:12:00.000”和“2017-11-01T16:35:00.000至2017-11-01T16:37:00.000”；该语句要求选择出满足任一时间区间的被选时间序列的值。")]),t._v(" "),a("p",[t._v("该SQL语句的执行结果如下：\n"),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/23614968/61280449-780fd480-a7ea-11e9-8ed0-70fa9dfda80f.png"}})])],1),t._v(" "),a("h4",{attrs:{id:"按照多个时间区间选择不同设备的多列数据"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#按照多个时间区间选择不同设备的多列数据"}},[t._v("#")]),t._v(" 按照多个时间区间选择不同设备的多列数据")]),t._v(" "),a("p",[t._v("该系统支持在一次查询中选择任意列的数据，也就是说，被选择的列可以来源于不同的设备。例如，SQL语句为：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select wf01.wt01.status,wf02.wt02.hardware from root.ln where (time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000) or (time >= 2017-11-01T16:35:00.000 and time <= 2017-11-01T16:37:00.000);\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("其含义为：")]),t._v(" "),a("p",[t._v("被选择的时间序列为“ln集团wf01子站wt01设备的供电状态”以及“ln集团wf02子站wt02设备的硬件版本”；该语句指定了两个时间区间，分别为“2017-11-01T00:05:00.000至2017-11-01T00:12:00.000”和“2017-11-01T16:35:00.000至2017-11-01T16:37:00.000”；该语句要求选择出满足任意时间区间的被选时间序列的值。")]),t._v(" "),a("p",[t._v("该SQL语句的执行结果如下：\n"),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577450-dcfe0800-1ef4-11e9-9399-4ba2b2b7fb73.jpg"}})])],1),t._v(" "),a("h4",{attrs:{id:"其他结果返回形式"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#其他结果返回形式"}},[t._v("#")]),t._v(" 其他结果返回形式")]),t._v(" "),a("p",[t._v("IoTDB支持另外两种结果返回形式: 按设备时间对齐 'align by device' 和 时序不对齐 'disable align'.")]),t._v(" "),a("p",[t._v("'align by device' 对齐方式下，设备ID会单独作为一列出现。在 select 子句中写了多少列，最终结果就会有该列数+2 （时间列和设备名字列）。SQL形如:")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select s1,s2 from root.sg1.* GROUP BY DEVICE\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("更多语法请参照 SQL REFERENCE.")]),t._v(" "),a("p",[t._v("'disable align' 意味着每条时序就有3列存在。更多语法请参照 SQL REFERENCE.")]),t._v(" "),a("h3",{attrs:{id:"聚合查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#聚合查询"}},[t._v("#")]),t._v(" 聚合查询")]),t._v(" "),a("p",[t._v("本章节主要介绍聚合查询的相关示例，\n主要使用的是IoTDB SELECT语句的聚合查询函数。")]),t._v(" "),a("h4",{attrs:{id:"统计总点数"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#统计总点数"}},[t._v("#")]),t._v(" 统计总点数")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status) from root.ln.wf01.wt01;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("table",[a("thead",[a("tr",[a("th",[t._v("count(root.ln.wf01.wt01.status)")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("4")])])])]),t._v(" "),a("h5",{attrs:{id:"按层级统计"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#按层级统计"}},[t._v("#")]),t._v(" 按层级统计")]),t._v(" "),a("p",[t._v("通过定义LEVEL来统计指定层级下的数据点个数。")]),t._v(" "),a("p",[t._v("这可以用来查询不同层级下的数据点总个数")]),t._v(" "),a("p",[t._v("语法是：")]),t._v(" "),a("p",[t._v("这个可以用来查询某个路径下的总数据点数")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status) from root.ln.wf01.wt01 group by level=1;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("table",[a("thead",[a("tr",[a("th",[t._v("Time")]),t._v(" "),a("th",[t._v("count(root.ln)")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("0")]),t._v(" "),a("td",[t._v("7")])])])]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status) from root.ln.wf01.wt01 group by level=2;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("table",[a("thead",[a("tr",[a("th",[t._v("Time")]),t._v(" "),a("th",[t._v("count(root.ln.wf01)")]),t._v(" "),a("th",[t._v("count(root.ln.wf02)")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("0")]),t._v(" "),a("td",[t._v("4")]),t._v(" "),a("td",[t._v("3")])])])]),t._v(" "),a("h3",{attrs:{id:"降频聚合查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#降频聚合查询"}},[t._v("#")]),t._v(" 降频聚合查询")]),t._v(" "),a("p",[t._v("本章节主要介绍降频聚合查询的相关示例，\n主要使用的是IoTDB SELECT语句的"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Operation Manual/SQL Reference.html"}},[t._v("GROUP BY子句")]),t._v("，\n该子句是IoTDB中用于根据用户给定划分条件对结果集进行划分，并对已划分的结果集进行聚合计算的语句。\nIoTDB支持根据时间间隔和自定义的滑动步长（默认值与时间间隔相同，自定义的值必须大于等于时间间隔）对结果集进行划分，默认结果按照时间升序排列。\n同时，您也可以使用Java JDBC标准接口来执行相关的查询语句。")],1),t._v(" "),a("p",[t._v("Group By 语句不支持 limit 和 offset。")]),t._v(" "),a("p",[t._v("GROUP BY语句为用户提供三类指定参数：")]),t._v(" "),a("ul",[a("li",[t._v("参数1：时间轴显示时间窗参数")]),t._v(" "),a("li",[t._v("参数2：划分时间轴的时间间隔参数（必须为正数）")]),t._v(" "),a("li",[t._v("参数3：滑动步长（可选参数，默认值与时间间隔相同，自定义的值必须大于等于时间间隔）")])]),t._v(" "),a("p",[t._v("三类参数的实际含义已经在图5.2中指出，这三类参数里，第三个参数是可选的。\n接下来，我们将给出三种典型的降频聚合查询的例子：\n滑动步长未指定，\n指定滑动步长，\n带值过滤条件。")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/16079446/69109512-f808bc80-0ab2-11ea-9e4d-b2b2f58fb474.png"}}),t._v("\n**图 5.2 三类参数的实际含义**")]),t._v(" "),a("h4",{attrs:{id:"未指定滑动步长的降频聚合查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#未指定滑动步长的降频聚合查询"}},[t._v("#")]),t._v(" 未指定滑动步长的降频聚合查询")]),t._v(" "),a("p",[t._v("对应的SQL语句是:")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01T00:00:00, 2017-11-07T23:00:00),1d);\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("这条查询的含义是:")]),t._v(" "),a("p",[t._v("由于用户没有指定滑动步长，滑动步长将会被默认设置为跟时间间隔参数相同，也就是"),a("code",[t._v("1d")]),t._v("。")]),t._v(" "),a("p",[t._v("上面这个例子的第一个参数是显示窗口参数，决定了最终的显示范围是[2017-11-01T00:00:00, 2017-11-07T23:00:00)。")]),t._v(" "),a("p",[t._v("上面这个例子的第二个参数是划分时间轴的时间间隔参数，将"),a("code",[t._v("1d")]),t._v("当作划分间隔，显示窗口参数的起始时间当作分割原点，时间轴即被划分为连续的时间间隔：[0,1d), [1d, 2d), [2d, 3d)等等。")]),t._v(" "),a("p",[t._v("然后系统将会用WHERE子句中的时间和值过滤条件以及GROUP BY语句中的第一个参数作为数据的联合过滤条件，获得满足所有过滤条件的数据（在这个例子里是在[2017-11-01T00:00:00, 2017-11-07 T23:00:00)这个时间范围的数据），并把这些数据映射到之前分割好的时间轴中（这个例子里是从2017-11-01T00:00:00到2017-11-07T23:00:00:00的每一天）")]),t._v(" "),a("p",[t._v("每个时间间隔窗口内都有数据，SQL执行后的结果集如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/16079446/69116068-eed51b00-0ac5-11ea-9731-b5a45c5cd224.png"}})]),t._v(" "),a("h4",{attrs:{id:"指定滑动步长的降频聚合查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#指定滑动步长的降频聚合查询"}},[t._v("#")]),t._v(" 指定滑动步长的降频聚合查询")]),t._v(" "),a("p",[t._v("对应的SQL语句是:")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01 00:00:00, 2017-11-07 23:00:00), 3h, 1d);\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("这条查询的含义是:")]),t._v(" "),a("p",[t._v("由于用户指定了滑动步长为"),a("code",[t._v("1d")]),t._v("，GROUP BY语句执行时将会每次把时间间隔往后移动一天的步长，而不是默认的3小时。")]),t._v(" "),a("p",[t._v("也就意味着，我们想要取从2017-11-01到2017-11-07每一天的凌晨0点到凌晨3点的数据。")]),t._v(" "),a("p",[t._v("上面这个例子的第一个参数是显示窗口参数，决定了最终的显示范围是[2017-11-01T00:00:00, 2017-11-07T23:00:00)。")]),t._v(" "),a("p",[t._v("上面这个例子的第二个参数是划分时间轴的时间间隔参数，将"),a("code",[t._v("3h")]),t._v("当作划分间隔，显示窗口参数的起始时间当作分割原点，时间轴即被划分为连续的时间间隔：[2017-11-01T00:00:00, 2017-11-01T03:00:00), [2017-11-02T00:00:00, 2017-11-02T03:00:00), [2017-11-03T00:00:00, 2017-11-03T03:00:00)等等。")]),t._v(" "),a("p",[t._v("上面这个例子的第三个参数是每次时间间隔的滑动步长。")]),t._v(" "),a("p",[t._v("然后系统将会用WHERE子句中的时间和值过滤条件以及GROUP BY语句中的第一个参数作为数据的联合过滤条件，获得满足所有过滤条件的数据（在这个例子里是在[2017-11-01T00:00:00, 2017-11-07 T23:00:00)这个时间范围的数据），并把这些数据映射到之前分割好的时间轴中（这个例子里是从2017-11-01T00:00:00到2017-11-07T23:00:00:00的每一天的凌晨0点到凌晨3点）")]),t._v(" "),a("p",[t._v("每个时间间隔窗口内都有数据，SQL执行后的结果集如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/16079446/69116083-f85e8300-0ac5-11ea-84f1-59d934eee96e.png"}})]),t._v(" "),a("h4",{attrs:{id:"带值过滤条件的降频聚合查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#带值过滤条件的降频聚合查询"}},[t._v("#")]),t._v(" 带值过滤条件的降频聚合查询")]),t._v(" "),a("p",[t._v("对应的SQL语句是:")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status), max_value(temperature) from root.ln.wf01.wt01 where time > 2017-11-01T01:00:00 and temperature > 20 group by([2017-11-01T00:00:00, 2017-11-07T23:00:00), 3h, 1d);\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("这条查询的含义是:")]),t._v(" "),a("p",[t._v("由于用户指定了滑动步长为"),a("code",[t._v("1d")]),t._v("，GROUP BY语句执行时将会每次把时间间隔往后移动一天的步长，而不是默认的3小时。")]),t._v(" "),a("p",[t._v("也就意味着，我们想要取从2017-11-01到2017-11-07每一天的凌晨0点到凌晨3点的数据。")]),t._v(" "),a("p",[t._v("上面这个例子的第一个参数是显示窗口参数，决定了最终的显示范围是[2017-11-01T00:00:00, 2017-11-07T23:00:00)。")]),t._v(" "),a("p",[t._v("上面这个例子的第二个参数是划分时间轴的时间间隔参数，将"),a("code",[t._v("3h")]),t._v("当作划分间隔，显示窗口参数的起始时间当作分割原点，时间轴即被划分为连续的时间间隔：[2017-11-01T00:00:00, 2017-11-01T03:00:00), [2017-11-02T00:00:00, 2017-11-02T03:00:00), [2017-11-03T00:00:00, 2017-11-03T03:00:00)等等。")]),t._v(" "),a("p",[t._v("上面这个例子的第三个参数是每次时间间隔的滑动步长。")]),t._v(" "),a("p",[t._v("然后系统将会用WHERE子句中的时间和值过滤条件以及GROUP BY语句中的第一个参数作为数据的联合过滤条件，获得满足所有过滤条件的数据（在这个例子里是在[2017-11-01T00:00:00, 2017-11-07 T23:00:00)这个时间范围的并且满足root.ln.wf01.wt01.temperature > 20的数据），并把这些数据映射到之前分割好的时间轴中（这个例子里是从2017-11-01T00:00:00到2017-11-07T23:00:00:00的每一天的凌晨0点到凌晨3点）")]),t._v(" "),a("p",[t._v("每个时间间隔窗口内都有数据，SQL执行后的结果集如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/16079446/69116088-001e2780-0ac6-11ea-9a01-dc45271d1dad.png"}})]),t._v(" "),a("p",[t._v("GROUP BY的SELECT子句里的查询路径必须是聚合函数，否则系统将会抛出如下对应的错误。")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/16079446/69116099-0b715300-0ac6-11ea-8074-84e04797b8c7.png"}})]),t._v(" "),a("h4",{attrs:{id:"左开右闭区间"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#左开右闭区间"}},[t._v("#")]),t._v(" 左开右闭区间")]),t._v(" "),a("p",[t._v("每个区间的结果时间戳为区间右端点，对应的SQL语句是:")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status) from root.ln.wf01.wt01 group by((5, 40], 5ms);\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("这条查询语句的时间区间是左开右闭的，结果中不会包含时间点5的数据，但是会包含时间点40的数据。")]),t._v(" "),a("p",[t._v("SQL执行后的结果集如下所示：")]),t._v(" "),a("table",[a("thead",[a("tr",[a("th",[t._v("Time")]),t._v(" "),a("th",[t._v("count(root.ln.wf01.wt01.status)")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("10")]),t._v(" "),a("td",[t._v("1")])]),t._v(" "),a("tr",[a("td",[t._v("15")]),t._v(" "),a("td",[t._v("2")])]),t._v(" "),a("tr",[a("td",[t._v("20")]),t._v(" "),a("td",[t._v("3")])]),t._v(" "),a("tr",[a("td",[t._v("25")]),t._v(" "),a("td",[t._v("4")])]),t._v(" "),a("tr",[a("td",[t._v("30")]),t._v(" "),a("td",[t._v("4")])]),t._v(" "),a("tr",[a("td",[t._v("35")]),t._v(" "),a("td",[t._v("3")])]),t._v(" "),a("tr",[a("td",[t._v("40")]),t._v(" "),a("td",[t._v("5")])])])]),t._v(" "),a("h4",{attrs:{id:"降采样后按level聚合查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#降采样后按level聚合查询"}},[t._v("#")]),t._v(" 降采样后按Level聚合查询")]),t._v(" "),a("p",[t._v("除此之外，还可以通过定义LEVEL来统计指定层级下的数据点个数。")]),t._v(" "),a("p",[t._v("例如：")]),t._v(" "),a("p",[t._v("统计降采样后的数据点个数")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status) from root.ln.wf01.wt01 group by ([0,20),3ms), level=1;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("table",[a("thead",[a("tr",[a("th",[t._v("Time")]),t._v(" "),a("th",[t._v("count(root.ln)")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("0")]),t._v(" "),a("td",[t._v("1")])]),t._v(" "),a("tr",[a("td",[t._v("3")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("6")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("9")]),t._v(" "),a("td",[t._v("1")])]),t._v(" "),a("tr",[a("td",[t._v("12")]),t._v(" "),a("td",[t._v("3")])]),t._v(" "),a("tr",[a("td",[t._v("15")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("18")]),t._v(" "),a("td",[t._v("0")])])])]),t._v(" "),a("p",[t._v("加上滑动Step的降采样后的结果也可以汇总")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status) from root.ln.wf01.wt01 group by ([0,20),2ms,3ms), level=1;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("table",[a("thead",[a("tr",[a("th",[t._v("Time")]),t._v(" "),a("th",[t._v("count(root.ln)")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("0")]),t._v(" "),a("td",[t._v("1")])]),t._v(" "),a("tr",[a("td",[t._v("3")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("6")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("9")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("12")]),t._v(" "),a("td",[t._v("2")])]),t._v(" "),a("tr",[a("td",[t._v("15")]),t._v(" "),a("td",[t._v("0")])]),t._v(" "),a("tr",[a("td",[t._v("18")]),t._v(" "),a("td",[t._v("0")])])])]),t._v(" "),a("h4",{attrs:{id:"降频聚合查询补空值"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#降频聚合查询补空值"}},[t._v("#")]),t._v(" 降频聚合查询补空值")]),t._v(" "),a("p",[t._v("降频聚合出的各个时间段的结果，支持使用前值补空。")]),t._v(" "),a("p",[t._v("不允许设置滑动步长，默认为聚合时间区间，实际为定长采样。现在只支持 last_value 聚合函数。")]),t._v(" "),a("p",[t._v("目前不支持线性插值补空值。")]),t._v(" "),a("h5",{attrs:{id:"previous-和-previousuntillast-的区别"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#previous-和-previousuntillast-的区别"}},[t._v("#")]),t._v(" PREVIOUS 和 PREVIOUSUNTILLAST 的区别")]),t._v(" "),a("ul",[a("li",[t._v("PREVIOUS：只要空值前边有值，就会用其填充空值。")]),t._v(" "),a("li",[t._v("PREVIOUSUNTILLAST：不会填充此序列最新点后的空值")])]),t._v(" "),a("p",[t._v("SQL 示例:")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("SELECT last_value(temperature) FROM root.ln.wf01.wt01 GROUP BY([8, 39), 5m) FILL (int32[PREVIOUSUNTILLAST])\nSELECT last_value(temperature) FROM root.ln.wf01.wt01 GROUP BY([8, 39), 5m) FILL (int32[PREVIOUSUNTILLAST, 3m])\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("解释:")]),t._v(" "),a("p",[t._v("使用 PREVIOUSUNTILLAST 方式填充降频聚合的结果。")]),t._v(" "),a("p",[t._v("所有路径必须都伴随聚合函数，否则会报以下错误信息：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/16079446/69116099-0b715300-0ac6-11ea-8074-84e04797b8c7.png"}})]),t._v(" "),a("h3",{attrs:{id:"最新数据查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#最新数据查询"}},[t._v("#")]),t._v(" 最新数据查询")]),t._v(" "),a("p",[t._v("SQL语法：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select last <Path> [COMMA <Path>]* from < PrefixPath > [COMMA < PrefixPath >]* <DISABLE ALIGN>\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("其含义是：查询时间序列prefixPath.path中最近时间戳的数据")]),t._v(" "),a("p",[t._v("结果集为三列的结构")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("| Time | Path | Value |\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("示例 1：查询 root.ln.wf01.wt01.speed 的最新数据点")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("> select last speed from root.ln.wf01.wt01\n\n| Time | Path                    | Value |\n| ---  | ----------------------- | ----- |\n|  5   | root.ln.wf01.wt01.speed | 100   |\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br"),a("span",{staticClass:"line-number"},[t._v("3")]),a("br"),a("span",{staticClass:"line-number"},[t._v("4")]),a("br"),a("span",{staticClass:"line-number"},[t._v("5")]),a("br")])]),a("p",[t._v("示例 2：查询 root.ln.wf01.wt01 下 speed，status，temperature 的最新数据点")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("> select last speed, status, temperature from root.ln.wf01\n\n| Time | Path                         | Value |\n| ---  | ---------------------------- | ----- |\n|  5   | root.ln.wf01.wt01.speed      | 100   |\n|  7   | root.ln.wf01.wt01.status     | true  |\n|  9   | root.ln.wf01.wt01.temperature| 35.7  |\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br"),a("span",{staticClass:"line-number"},[t._v("3")]),a("br"),a("span",{staticClass:"line-number"},[t._v("4")]),a("br"),a("span",{staticClass:"line-number"},[t._v("5")]),a("br"),a("span",{staticClass:"line-number"},[t._v("6")]),a("br"),a("span",{staticClass:"line-number"},[t._v("7")]),a("br")])]),a("h3",{attrs:{id:"自动填充"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#自动填充"}},[t._v("#")]),t._v(" 自动填充")]),t._v(" "),a("p",[t._v("在IoTDB的实际使用中，当进行时间序列的查询操作时，可能会出现在某些时间点值为null的情况，这会妨碍用户进行进一步的分析。 为了更好地反映数据更改的程度，用户希望可以自动填充缺失值。 因此，IoTDB系统引入了自动填充功能。")]),t._v(" "),a("p",[t._v("自动填充功能是指对单列或多列执行时间序列查询时，根据用户指定的方法和有效时间范围填充空值。 如果查询点的值不为null，则填充功能将不起作用。")]),t._v(" "),a("blockquote",[a("p",[t._v("注意：在当前版本中，IoTDB为用户提供两种方法：Previous 和Linear。 Previous 方法用前一个值填充空白。 Linear方法通过线性拟合来填充空白。 并且填充功能只能在执行时间点查询时使用。")])]),t._v(" "),a("h4",{attrs:{id:"填充功能"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#填充功能"}},[t._v("#")]),t._v(" 填充功能")]),t._v(" "),a("ul",[a("li",[t._v("Previous功能")])]),t._v(" "),a("p",[t._v("当查询的时间戳值为空时，将使用前一个时间戳的值来填充空白。 形式化的先前方法如下（有关详细语法，请参见第7.1.3.6节）：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select <path> from <prefixPath> where time = <T> fill(<data_type>[previous, <before_range>], …)\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("表3-4给出了所有参数的详细说明。")]),t._v(" "),a("center",[t._v("**表3-4previous填充参数列表**\n"),a("table",[a("thead",[a("tr",[a("th",{staticStyle:{"text-align":"left"}},[t._v("参数名称（不区分大小写）")]),t._v(" "),a("th",{staticStyle:{"text-align":"left"}},[t._v("解释")])])]),t._v(" "),a("tbody",[a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("path, prefixPath")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("查询路径； 必填项")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("T")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("查询时间戳（只能指定一个）； 必填项")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("data_type")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("填充方法使用的数据类型。 可选值是int32，int64，float，double，boolean，text; 可选字段")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("before_range")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("表示前一种方法的有效时间范围。 当[T-before \\ _range，T]范围内的值存在时，前一种方法将起作用。 如果未指定before_range，则before_range会使用默认值default_fill_interval; -1表示无穷大； 可选字段")])])])])]),t._v(" "),a("p",[t._v("在这里，我们举一个使用先前方法填充空值的示例。 SQL语句如下：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select temperature from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float[previous, 1m]) \n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("由于时间根目录root.sgcc.wf03.wt01.temperature在2017-11-01T16：37：50.000为空，因此系统使用以前的时间戳2017-11-01T16：37：00.000（且时间戳位于[2017-11-01T16:36:50.000, 2017-11-01T16:37:50.000]范围）进行填充和显示。")]),t._v(" "),a("p",[t._v("在"),a("a",{attrs:{href:"https://github.com/thulab/iotdb/files/4438687/OtherMaterial-Sample.Data.txt",target:"_blank",rel:"noopener noreferrer"}},[t._v("样例数据中"),a("OutboundLink")],1),t._v(", 该语句的执行结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577616-67df0280-1ef5-11e9-9dff-2eb8342074eb.jpg"}})]),t._v(" "),a("p",[t._v("值得注意的是，如果在指定的有效时间范围内没有值，系统将不会填充空值，如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577679-9f4daf00-1ef5-11e9-8d8b-06a58de6efc1.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("Linear方法")])]),t._v(" "),a("p",[t._v("当查询的时间戳值为空时，将使用前一个和下一个时间戳的值来填充空白。 形式化线性方法如下：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select <path> from <prefixPath> where time = <T> fill(<data_type>[linear, <before_range>, <after_range>]…)\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("表3-5中给出了所有参数的详细说明。")]),t._v(" "),a("center",[t._v("**表3-5线性填充参数列表**\n"),a("table",[a("thead",[a("tr",[a("th",{staticStyle:{"text-align":"left"}},[t._v("参数名称（不区分大小写）")]),t._v(" "),a("th",{staticStyle:{"text-align":"left"}},[t._v("解释")])])]),t._v(" "),a("tbody",[a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("path, prefixPath")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("查询路径； 必填项")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("T")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("查询时间戳（只能指定一个）； 必填项")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("data_type")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("填充方法使用的数据类型。 可选值是int32，int64，float，double，boolean，text; 可选字段")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("before_range, after_range")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("表示线性方法的有效时间范围。 当[T-before_range，T + after_range]范围内的值存在时，前一种方法将起作用。 如果未明确指定before_range和after_range，则使用default_fill_interval。 -1表示无穷大； 可选字段")])])])])]),t._v(" "),a("p",[t._v("需要注意的是一旦时间序列在查询时间戳T时刻存在有效值，线性填充就回使用这个值作为结果返回。\n除此之外，如果在[T-before_range，T]或[T, T + after_range]两个范围中任意一个范围内不存在有效填充值，则线性填充返回null值。")]),t._v(" "),a("p",[t._v("在这里，我们举一个使用线性方法填充空值的示例。 SQL语句如下：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select temperature from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float [linear, 1m, 1m])\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("由于时间根目录root.sgcc.wf03.wt01.temperature在2017-11-01T16：37：50.000为空，因此系统使用以前的时间戳2017-11-01T16：37：00.000（且时间戳位于[2017- 11-01T16：36：50.000，2017-11-01T16：37：50.000]时间范围）及其值21.927326，下一个时间戳记2017-11-01T16：38：00.000（且时间戳记位于[2017-11-11] 01T16：37：50.000、2017-11-01T16：38：50.000]时间范围）及其值25.311783以执行线性拟合计算：")]),t._v(" "),a("p",[t._v("21.927326 +（25.311783-21.927326）/ 60s * 50s = 24.747707")]),t._v(" "),a("p",[t._v("在 "),a("a",{attrs:{href:"https://github.com/thulab/iotdb/files/4438687/OtherMaterial-Sample.Data.txt",target:"_blank",rel:"noopener noreferrer"}},[t._v("样例数据"),a("OutboundLink")],1),t._v(", 该语句的执行结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577727-d4f29800-1ef5-11e9-8ff3-3bb519da3993.jpg"}})]),t._v(" "),a("h4",{attrs:{id:"数据类型和填充方法之间的对应关系"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#数据类型和填充方法之间的对应关系"}},[t._v("#")]),t._v(" 数据类型和填充方法之间的对应关系")]),t._v(" "),a("p",[t._v("数据类型和支持的填充方法如表3-6所示。")]),t._v(" "),a("center",[t._v("**表3-6数据类型和支持的填充方法**\n"),a("table",[a("thead",[a("tr",[a("th",{staticStyle:{"text-align":"left"}},[t._v("数据类型")]),t._v(" "),a("th",{staticStyle:{"text-align":"left"}},[t._v("支持的填充方法")])])]),t._v(" "),a("tbody",[a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("boolean")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("int32")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous, linear")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("int64")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous, linear")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("float")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous, linear")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("double")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous, linear")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("text")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous")])])])])]),t._v(" "),a("p",[t._v("值得注意的是，IoTDB将针对数据类型不支持的填充方法给出错误提示，如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577741-e340b400-1ef5-11e9-9238-a4eaf498ab84.jpg"}})]),t._v(" "),a("p",[t._v("如果未指定fill方法，则每种数据类型均具有其自己的默认fill方法和参数。 对应关系如表3-7所示。")]),t._v(" "),a("center",[t._v("**表3-7各种数据类型的默认填充方法和参数**\n"),a("table",[a("thead",[a("tr",[a("th",{staticStyle:{"text-align":"left"}},[t._v("数据类型")]),t._v(" "),a("th",{staticStyle:{"text-align":"left"}},[t._v("默认填充方法和参数")])])]),t._v(" "),a("tbody",[a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("boolean")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous, 600000")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("int32")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("linear, 600000, 600000")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("int64")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("linear, 600000, 600000")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("float")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("linear, 600000, 600000")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("double")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("linear, 600000, 600000")])]),t._v(" "),a("tr",[a("td",{staticStyle:{"text-align":"left"}},[t._v("text")]),t._v(" "),a("td",{staticStyle:{"text-align":"left"}},[t._v("previous, 600000")])])])])]),t._v(" "),a("blockquote",[a("p",[t._v("注意：应在Fill语句中至少指定一种填充方法。")])]),t._v(" "),a("h3",{attrs:{id:"对查询结果的行和列控制"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#对查询结果的行和列控制"}},[t._v("#")]),t._v(" 对查询结果的行和列控制")]),t._v(" "),a("p",[t._v("IoTDB提供 "),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Operation Manual/SQL Reference.html"}},[t._v("LIMIT/SLIMIT")]),t._v(" 子句和 "),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Operation Manual/SQL Reference.html"}},[t._v("OFFSET/SOFFSET")]),t._v(" 子句，以使用户可以更好地控制查询结果。使用LIMIT和SLIMIT子句可让用户控制查询结果的行数和列数，\n并且使用OFFSET和SOFSET子句允许用户设置结果显示的起始位置。")],1),t._v(" "),a("p",[t._v("请注意，按组查询不支持LIMIT和OFFSET。")]),t._v(" "),a("p",[t._v("本章主要介绍查询结果的行和列控制的相关示例。你还可以使用 "),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Client/Programming - JDBC.html"}},[t._v("Java JDBC")]),t._v(" 标准接口执行查询。")],1),t._v(" "),a("h4",{attrs:{id:"查询结果的行控制"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#查询结果的行控制"}},[t._v("#")]),t._v(" 查询结果的行控制")]),t._v(" "),a("p",[t._v("通过使用LIMIT和OFFSET子句，用户可以以与行相关的方式控制查询结果。 我们将通过以下示例演示如何使用LIMIT和OFFSET子句。")]),t._v(" "),a("ul",[a("li",[t._v("示例1：基本的LIMIT子句")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status, temperature from root.ln.wf01.wt01 limit 10\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 选择的时间序列是“状态”和“温度”。 SQL语句要求返回查询结果的前10行。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577752-efc50c80-1ef5-11e9-9071-da2bbd8b9bdd.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("示例2：带OFFSET的LIMIT子句")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status, temperature from root.ln.wf01.wt01 limit 5 offset 3\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 选择的时间序列是“状态”和“温度”。 SQL语句要求返回查询结果的第3至7行（第一行编号为0行）。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577773-08352700-1ef6-11e9-883f-8d353bef2bdc.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("示例3：LIMIT子句与WHERE子句结合")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time< 2017-11-01T00:12:00.000 limit 2 offset 3\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 选择的时间序列是“状态”和“温度”。 SQL语句要求返回时间“ 2017-11-01T00：05：00.000”和“ 2017-11-01T00：12：00.000”之间的状态和温度传感器值的第3至4行（第一行） 编号为第0行）。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577789-15521600-1ef6-11e9-86ca-d7b2c947367f.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("示例4：LIMIT子句与GROUP BY子句组合")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01T00:00:00, 2017-11-07T23:00:00),1d) limit 5 offset 3\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("SQL语句子句要求返回查询结果的第3至7行（第一行编号为0行）。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577796-1e42e780-1ef6-11e9-8987-be443000a77e.jpg"}})]),t._v(" "),a("p",[t._v("值得注意的是，由于当前的FILL子句只能在某个时间点填充时间序列的缺失值，也就是说，FILL子句的执行结果恰好是一行，因此LIMIT和OFFSET不会是 与FILL子句结合使用，否则将提示错误。 例如，执行以下SQL语句：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select temperature from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float[previous, 1m]) limit 10\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("SQL语句将不会执行，并且相应的错误提示如下：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/19167280/61517266-6e2fe080-aa39-11e9-8015-154a8e8ace30.png"}})]),t._v(" "),a("h4",{attrs:{id:"查询结果的列控制"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#查询结果的列控制"}},[t._v("#")]),t._v(" 查询结果的列控制")]),t._v(" "),a("p",[t._v("通过使用LIMIT和OFFSET子句，用户可以以与列相关的方式控制查询结果。 我们将通过以下示例演示如何使用SLIMIT和OFFSET子句。")]),t._v(" "),a("ul",[a("li",[t._v("示例1：基本的SLIMIT子句")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select * from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 所选时间序列是该设备下的第一列，即电源状态。 SQL语句要求在“ 2017-11-01T00：05：00.000”和“ 2017-11-01T00：12：00.000”的时间点之间选择状态传感器值。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577813-30bd2100-1ef6-11e9-94ef-dbeb450cf319.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("示例2：带OFFSET的LIMIT子句")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select * from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1 soffset 1\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 所选时间序列是该设备下的第二列，即温度。 SQL语句要求在“ 2017-11-01T00：05：00.000”和“ 2017-11-01T00：12：00.000”的时间点之间选择温度传感器值。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577827-39adf280-1ef6-11e9-81b5-876769607cd2.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("示例3：SLIMIT子句与GROUP BY子句结合")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select max_value(*) from root.ln.wf01.wt01 group by ([2017-11-01T00:00:00, 2017-11-07T23:00:00),1d) slimit 1 soffset 1\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577840-44688780-1ef6-11e9-8abc-04ae78efa85b.jpg"}})]),t._v(" "),a("ul",[a("li",[t._v("示例4：SLIMIT子句与FILL子句结合")])]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select * from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float[previous, 1m]) slimit 1 soffset 1\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 所选时间序列是该设备下的第二列，即温度。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577855-4d595900-1ef6-11e9-8541-a4accd714b75.jpg"}})]),t._v(" "),a("p",[t._v("值得注意的是，预期SLIMIT子句将与星形路径或前缀路径一起使用，并且当SLIMIT子句与完整路径查询一起使用时，系统将提示错误。 例如，执行以下SQL语句：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("SQL语句将不会执行，并且相应的错误提示如下：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577867-577b5780-1ef6-11e9-978c-e02c1294bcc5.jpg"}})]),t._v(" "),a("h4",{attrs:{id:"控制查询结果的行和列"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#控制查询结果的行和列"}},[t._v("#")]),t._v(" 控制查询结果的行和列")]),t._v(" "),a("p",[t._v("除了对查询结果进行行或列控制之外，IoTDB还允许用户控制查询结果的行和列。 这是同时包含LIMIT子句和SLIMIT子句的完整示例。")]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select * from root.ln.wf01.wt01 limit 10 offset 100 slimit 2 soffset 0\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("意思是：")]),t._v(" "),a("p",[t._v("所选设备为ln组wf01工厂wt01设备； 所选时间序列是此设备下的第0列至第1列（第一列编号为第0列）。 SQL语句子句要求返回查询结果的第100至109行（第一行编号为0行）。")]),t._v(" "),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577879-64984680-1ef6-11e9-9d7b-57dd60fab60e.jpg"}})]),t._v(" "),a("h4",{attrs:{id:"其他结果集格式"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#其他结果集格式"}},[t._v("#")]),t._v(" 其他结果集格式")]),t._v(" "),a("p",[t._v("此外，IoTDB支持两种其他结果集格式：“按设备对齐”和“禁用对齐”。")]),t._v(" "),a("p",[t._v("“按设备对齐”指示将deviceId视为一列。 因此，数据集中的列完全有限。")]),t._v(" "),a("p",[t._v("SQL语句是：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select s1,s2 from root.sg1.* GROUP BY DEVICE\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("有关更多语法描述，请阅读SQL REFERENCE。")]),t._v(" "),a("p",[t._v("“禁用对齐”指示结果集中每个时间序列都有3列。 有关更多语法描述，请阅读SQL REFERENCE。")]),t._v(" "),a("h4",{attrs:{id:"错误处理"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#错误处理"}},[t._v("#")]),t._v(" 错误处理")]),t._v(" "),a("p",[t._v("当LIMIT / SLIMIT的参数N / SN超过结果集的大小时，IoTDB将按预期返回所有结果。 例如，原始SQL语句的查询结果由六行组成，我们通过LIMIT子句选择前100行：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 100\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51578187-ad9cca80-1ef7-11e9-897a-83e66a0f3d94.jpg"}})]),t._v(" "),a("p",[t._v("当LIMIT / SLIMIT子句的参数N / SN超过允许的最大值（N / SN的类型为int32）时，系统将提示错误。 例如，执行以下SQL语句：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 1234567890123456789\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("SQL语句将不会执行，并且相应的错误提示如下：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/19167280/61517469-e696a180-aa39-11e9-8ca5-42ea991d520e.png"}})]),t._v(" "),a("p",[t._v("当LIMIT / LIMIT子句的参数N / SN不是正整数时，系统将提示错误。 例如，执行以下SQL语句：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 13.1\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("SQL语句将不会执行，并且相应的错误提示如下：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/19167280/61518094-68d39580-aa3b-11e9-993c-fc73c27540f7.png"}})]),t._v(" "),a("p",[t._v("当LIMIT子句的参数OFFSET超过结果集的大小时，IoTDB将返回空结果集。 例如，执行以下SQL语句：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 2 offset 6\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("结果如下所示：")]),t._v(" "),a("center",[a("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51578227-c60ce500-1ef7-11e9-98eb-175beb8d4086.jpg"}})]),t._v(" "),a("p",[t._v("当SLIMIT子句的参数SOFFSET不小于可用时间序列数时，系统将提示错误。 例如，执行以下SQL语句：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("select * from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1 soffset 2\n\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])]),a("p",[t._v("SQL语句将不会执行，并且相应的错误提示如下：")]),t._v(" "),a("h3",{attrs:{id:"数据删除"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#数据删除"}},[t._v("#")]),t._v(" 数据删除")]),t._v(" "),a("p",[t._v("用户使用"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Operation Manual/SQL Reference.html"}},[t._v("DELETE语句")]),t._v("可以删除指定的时间序列中符合时间删除条件的数据。在删除数据时，用户可以选择需要删除的一个或多个时间序列、时间序列的前缀、时间序列带*路径对某时间之前的数据进行删除（当前版本暂不支持删除某一闭时间区间范围内的数据）。")],1),t._v(" "),a("p",[t._v("在JAVA编程环境中，您可以使用JDBC API单条或批量执行DELETE语句。")]),t._v(" "),a("h4",{attrs:{id:"单传感器时间序列值删除"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#单传感器时间序列值删除"}},[t._v("#")]),t._v(" 单传感器时间序列值删除")]),t._v(" "),a("p",[t._v("以测控ln集团为例，存在这样的使用场景：")]),t._v(" "),a("p",[t._v("wf02子站的wt02设备在2017-11-01 16:26:00之前的供电状态出现多段错误，且无法分析其正确数据，错误数据影响了与其他设备的关联分析。此时，需要将此时间段前的数据删除。进行此操作的SQL语句为：")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("delete from root.ln.wf02.wt02.status where time<=2017-11-01T16:26:00;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("h4",{attrs:{id:"多传感器时间序列值删除"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#多传感器时间序列值删除"}},[t._v("#")]),t._v(" 多传感器时间序列值删除")]),t._v(" "),a("p",[t._v("当ln集团wf02子站的wt02设备在2017-11-01 16:26:00之前的供电状态和设备硬件版本都需要删除，此时可以使用含义更广的"),a("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Concept/Data Model and Terminology.html"}},[t._v("前缀路径或带"),a("code",[t._v("*")]),t._v("路径")]),t._v("进行删除操作，进行此操作的SQL语句为：")],1),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("delete from root.ln.wf02.wt02 where time <= 2017-11-01T16:26:00;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("或")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("delete from root.ln.wf02.wt02.* where time <= 2017-11-01T16:26:00;\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("需要注意的是，当删除的路径不存在时，IoTDB会提示路径不存在，无法删除数据，如下所示。")]),t._v(" "),a("div",{staticClass:"language- line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("IoTDB> delete from root.ln.wf03.wt02.status where time < now()\nMsg: TimeSeries does not exist and its data cannot be deleted\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br"),a("span",{staticClass:"line-number"},[t._v("2")]),a("br")])])],1)}),[],!1,null,null,null);e.default=r.exports}}]);