assets/Conversion.html-SRI9g9ph.js - iotdb-website - Git at Google

 import{_ as t,o as s,c as e,e as n}from"./app-Bp5kEZWW.js";const a={},o=n(`<h1 id="数据类型转换" tabindex="-1"><a class="header-anchor" href="#数据类型转换"><span>数据类型转换</span></a></h1><h2 id="cast" tabindex="-1"><a class="header-anchor" href="#cast"><span>CAST</span></a></h2><h3 id="函数简介" tabindex="-1"><a class="header-anchor" href="#函数简介"><span>函数简介</span></a></h3><p>当前IoTDB支持6种数据类型，其中包括INT32、INT64、FLOAT、DOUBLE、BOOLEAN以及TEXT。当我们对数据进行查询或者计算时可能需要进行数据类型的转换， 比如说将TEXT转换为INT32，或者提高数据精度，比如说将FLOAT转换为DOUBLE。所以，IoTDB支持使用cast函数对数据类型进行转换。</p><table><thead><tr><th>函数名</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>CAST</td><td><code>type</code>:输出的数据点的类型，只能是 INT32 / INT64 / FLOAT / DOUBLE / BOOLEAN / TEXT</td><td>由输入属性参数<code>type</code>决定</td><td>将数据转换为<code>type</code>参数指定的类型。</td></tr></tbody></table><h3 id="类型转换说明" tabindex="-1"><a class="header-anchor" href="#类型转换说明"><span>类型转换说明</span></a></h3><p>1.当INT32、INT64类型的值不为0时，FLOAT与DOUBLE类型的值不为0.0时，TEXT类型不为空字符串或者&quot;false&quot;时，转换为BOOLEAN类型时值为true，否则为false。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; show timeseries root.sg.d1.*;
 +-------------+-----+-------------+--------+--------+-----------+----+----------+
 |   timeseries|alias|     database|dataType|encoding|compression|tags|attributes|
 +-------------+-----+-------------+--------+--------+-----------+----+----------+
 |root.sg.d1.s3| null|      root.sg|   FLOAT|     RLE|     SNAPPY|null|      null|
 |root.sg.d1.s4| null|      root.sg|  DOUBLE|     RLE|     SNAPPY|null|      null|
 |root.sg.d1.s5| null|      root.sg|    TEXT|   PLAIN|     SNAPPY|null|      null|
 |root.sg.d1.s6| null|      root.sg| BOOLEAN|     RLE|     SNAPPY|null|      null|
 |root.sg.d1.s1| null|      root.sg|   INT32|     RLE|     SNAPPY|null|      null|
 |root.sg.d1.s2| null|      root.sg|   INT64|     RLE|     SNAPPY|null|      null|
 +-------------+-----+-------------+--------+--------+-----------+----+----------+
 Total line number = 6
 It costs 0.006s
 IoTDB&gt; select * from root.sg.d1;
 +-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
 |                         Time|root.sg.d1.s3|root.sg.d1.s4|root.sg.d1.s5|root.sg.d1.s6|root.sg.d1.s1|root.sg.d1.s2|
 +-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
 |1970-01-01T08:00:00.001+08:00|          1.1|          1.1|         test|        false|            1|            1|
 |1970-01-01T08:00:00.002+08:00|         -2.2|         -2.2|        false|         true|           -2|           -2|
 |1970-01-01T08:00:00.003+08:00|          0.0|          0.0|         true|         true|            0|            0|
 +-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
 Total line number = 3
 It costs 0.009s
 IoTDB&gt; select cast(s1, &#39;type&#39;=&#39;BOOLEAN&#39;), cast(s2, &#39;type&#39;=&#39;BOOLEAN&#39;), cast(s3, &#39;type&#39;=&#39;BOOLEAN&#39;), cast(s4, &#39;type&#39;=&#39;BOOLEAN&#39;), cast(s5, &#39;type&#39;=&#39;BOOLEAN&#39;) from root.sg.d1;
 +-----------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+
 |                         Time|cast(root.sg.d1.s1, &quot;type&quot;=&quot;BOOLEAN&quot;)|cast(root.sg.d1.s2, &quot;type&quot;=&quot;BOOLEAN&quot;)|cast(root.sg.d1.s3, &quot;type&quot;=&quot;BOOLEAN&quot;)|cast(root.sg.d1.s4, &quot;type&quot;=&quot;BOOLEAN&quot;)|cast(root.sg.d1.s5, &quot;type&quot;=&quot;BOOLEAN&quot;)|
 +-----------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+
 |1970-01-01T08:00:00.001+08:00|                                 true|                                 true|                                 true|                                 true|                                 true|
 |1970-01-01T08:00:00.002+08:00|                                 true|                                 true|                                 true|                                 true|                                false|
 |1970-01-01T08:00:00.003+08:00|                                false|                                false|                                false|                                false|                                 true|
 +-----------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+
 Total line number = 3
 It costs 0.012s
 </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>2.当BOOLEAN类型的值为true时，转换为INT32与INT64类型的值为1，转换为FLOAT或者DOUBLE类型时值为1.0，转换为TEXT类型时值为&quot;true&quot;。当BOOLEAN类型的值为false时，转换为INT32与INT64类型的值为0，转换为FLOAT或者DOUBLE类型时值为0.0，转换为TEXT类型时值为&quot;false&quot;。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; select cast(s6, &#39;type&#39;=&#39;INT32&#39;), cast(s6, &#39;type&#39;=&#39;INT64&#39;), cast(s6, &#39;type&#39;=&#39;FLOAT&#39;), cast(s6, &#39;type&#39;=&#39;DOUBLE&#39;), cast(s6, &#39;type&#39;=&#39;TEXT&#39;) from root.sg.d1;
 +-----------------------------+-----------------------------------+-----------------------------------+-----------------------------------+------------------------------------+----------------------------------+
 |                         Time|cast(root.sg.d1.s6, &quot;type&quot;=&quot;INT32&quot;)|cast(root.sg.d1.s6, &quot;type&quot;=&quot;INT64&quot;)|cast(root.sg.d1.s6, &quot;type&quot;=&quot;FLOAT&quot;)|cast(root.sg.d1.s6, &quot;type&quot;=&quot;DOUBLE&quot;)|cast(root.sg.d1.s6, &quot;type&quot;=&quot;TEXT&quot;)|
 +-----------------------------+-----------------------------------+-----------------------------------+-----------------------------------+------------------------------------+----------------------------------+
 |1970-01-01T08:00:00.001+08:00|                                  0|                                  0|                                0.0|                                 0.0|                             false|
 |1970-01-01T08:00:00.002+08:00|                                  1|                                  1|                                1.0|                                 1.0|                              true|
 |1970-01-01T08:00:00.003+08:00|                                  1|                                  1|                                1.0|                                 1.0|                              true|
 +-----------------------------+-----------------------------------+-----------------------------------+-----------------------------------+------------------------------------+----------------------------------+
 Total line number = 3
 It costs 0.016s
 </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>3.当TEXT类型转换为INT32、INT64、FLOAT类型时，会先将TEXT类型的数据转换为DOUBLE类型，然后再转换为对应的类型，此时可能会存在损失精度的问题。如果无法转换的话则直接跳过。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; select cast(s5, &#39;type&#39;=&#39;INT32&#39;), cast(s5, &#39;type&#39;=&#39;INT64&#39;), cast(s5, &#39;type&#39;=&#39;FLOAT&#39;) from root.sg.d1;
 +----+-----------------------------------+-----------------------------------+-----------------------------------+
 |Time|cast(root.sg.d1.s5, &quot;type&quot;=&quot;INT32&quot;)|cast(root.sg.d1.s5, &quot;type&quot;=&quot;INT64&quot;)|cast(root.sg.d1.s5, &quot;type&quot;=&quot;FLOAT&quot;)|
 +----+-----------------------------------+-----------------------------------+-----------------------------------+
 +----+-----------------------------------+-----------------------------------+-----------------------------------+
 Empty set.
 It costs 0.009s
 </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="使用示例" tabindex="-1"><a class="header-anchor" href="#使用示例"><span>使用示例</span></a></h3><p>测试数据：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; select text from root.test;
 +-----------------------------+--------------+
 |                         Time|root.test.text|
 +-----------------------------+--------------+
 |1970-01-01T08:00:00.001+08:00|           1.1|
 |1970-01-01T08:00:00.002+08:00|             1|
 |1970-01-01T08:00:00.003+08:00|   hello world|
 |1970-01-01T08:00:00.004+08:00|         false|
 +-----------------------------+--------------+
 </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>SQL语句：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">&#39;type&#39;</span><span class="token operator">=</span><span class="token string">&#39;BOOLEAN&#39;</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">&#39;type&#39;</span><span class="token operator">=</span><span class="token string">&#39;INT32&#39;</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">&#39;type&#39;</span><span class="token operator">=</span><span class="token string">&#39;INT64&#39;</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">&#39;type&#39;</span><span class="token operator">=</span><span class="token string">&#39;FLOAT&#39;</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">&#39;type&#39;</span><span class="token operator">=</span><span class="token string">&#39;DOUBLE&#39;</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>test<span class="token punctuation">;</span>
 </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+--------------------------------------+------------------------------------+------------------------------------+------------------------------------+-------------------------------------+
 |                         Time|cast(root.test.text, &quot;type&quot;=&quot;BOOLEAN&quot;)|cast(root.test.text, &quot;type&quot;=&quot;INT32&quot;)|cast(root.test.text, &quot;type&quot;=&quot;INT64&quot;)|cast(root.test.text, &quot;type&quot;=&quot;FLOAT&quot;)|cast(root.test.text, &quot;type&quot;=&quot;DOUBLE&quot;)|
 +-----------------------------+--------------------------------------+------------------------------------+------------------------------------+------------------------------------+-------------------------------------+
 |1970-01-01T08:00:00.001+08:00|                                  true|                                   1|                                   1|                                 1.1|                                  1.1|
 |1970-01-01T08:00:00.002+08:00|                                  true|                                   1|                                   1|                                 1.0|                                  1.0|
 |1970-01-01T08:00:00.003+08:00|                                  true|                                null|                                null|                                null|                                 null|
 |1970-01-01T08:00:00.004+08:00|                                 false|                                null|                                null|                                null|                                 null|
 +-----------------------------+--------------------------------------+------------------------------------+------------------------------------+------------------------------------+-------------------------------------+
 Total line number = 4
 It costs 0.078s
 </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,19),i=[o];function l(d,r){return s(),e("div",null,i)}const c=t(a,[["render",l],["__file","Conversion.html.vue"]]),p=JSON.parse('{"path":"/zh/UserGuide/V1.0.x/Operators-Functions/Conversion.html","title":"数据类型转换","lang":"zh-CN","frontmatter":{"description":"数据类型转换 CAST 函数简介 当前IoTDB支持6种数据类型，其中包括INT32、INT64、FLOAT、DOUBLE、BOOLEAN以及TEXT。当我们对数据进行查询或者计算时可能需要进行数据类型的转换， 比如说将TEXT转换为INT32，或者提高数据精度，比如说将FLOAT转换为DOUBLE。所以，IoTDB支持使用cast函数对数据类型进行转...","head":[["link",{"rel":"alternate","hreflang":"en-us","href":"https://iotdb.apache.org/UserGuide/V1.0.x/Operators-Functions/Conversion.html"}],["meta",{"property":"og:url","content":"https://iotdb.apache.org/zh/UserGuide/V1.0.x/Operators-Functions/Conversion.html"}],["meta",{"property":"og:site_name","content":"IoTDB Website"}],["meta",{"property":"og:title","content":"数据类型转换"}],["meta",{"property":"og:description","content":"数据类型转换 CAST 函数简介 当前IoTDB支持6种数据类型，其中包括INT32、INT64、FLOAT、DOUBLE、BOOLEAN以及TEXT。当我们对数据进行查询或者计算时可能需要进行数据类型的转换， 比如说将TEXT转换为INT32，或者提高数据精度，比如说将FLOAT转换为DOUBLE。所以，IoTDB支持使用cast函数对数据类型进行转..."}],["meta",{"property":"og:type","content":"article"}],["meta",{"property":"og:locale","content":"zh-CN"}],["meta",{"property":"og:locale:alternate","content":"en-US"}],["meta",{"property":"og:updated_time","content":"2023-07-10T03:11:17.000Z"}],["meta",{"property":"article:modified_time","content":"2023-07-10T03:11:17.000Z"}],["script",{"type":"application/ld+json"},"{\\"@context\\":\\"https://schema.org\\",\\"@type\\":\\"Article\\",\\"headline\\":\\"数据类型转换\\",\\"image\\":[\\"\\"],\\"dateModified\\":\\"2023-07-10T03:11:17.000Z\\",\\"author\\":[]}"]]},"headers":[{"level":2,"title":"CAST","slug":"cast","link":"#cast","children":[{"level":3,"title":"函数简介","slug":"函数简介","link":"#函数简介","children":[]},{"level":3,"title":"类型转换说明","slug":"类型转换说明","link":"#类型转换说明","children":[]},{"level":3,"title":"使用示例","slug":"使用示例","link":"#使用示例","children":[]}]}],"git":{"createdTime":1688958677000,"updatedTime":1688958677000,"contributors":[{"name":"CritasWang","email":"critas@outlook.com","commits":1}]},"readingTime":{"minutes":3.3,"words":989},"filePathRelative":"zh/UserGuide/V1.0.x/Operators-Functions/Conversion.md","localizedDate":"2023年7月10日","autoDesc":true}');export{c as comp,p as data};
	import{_ as t,o as s,c as e,e as n}from"./app-Bp5kEZWW.js";const a={},o=n(`<h1 id="数据类型转换" tabindex="-1"><a class="header-anchor" href="#数据类型转换"><span>数据类型转换</span></a></h1><h2 id="cast" tabindex="-1"><a class="header-anchor" href="#cast"><span>CAST</span></a></h2><h3 id="函数简介" tabindex="-1"><a class="header-anchor" href="#函数简介"><span>函数简介</span></a></h3><p>当前IoTDB支持6种数据类型，其中包括INT32、INT64、FLOAT、DOUBLE、BOOLEAN以及TEXT。当我们对数据进行查询或者计算时可能需要进行数据类型的转换，比如说将TEXT转换为INT32，或者提高数据精度，比如说将FLOAT转换为DOUBLE。所以，IoTDB支持使用cast函数对数据类型进行转换。</p><table><thead><tr><th>函数名</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>CAST</td><td><code>type</code>:输出的数据点的类型，只能是 INT32 / INT64 / FLOAT / DOUBLE / BOOLEAN / TEXT</td><td>由输入属性参数<code>type</code>决定</td><td>将数据转换为<code>type</code>参数指定的类型。</td></tr></tbody></table><h3 id="类型转换说明" tabindex="-1"><a class="header-anchor" href="#类型转换说明"><span>类型转换说明</span></a></h3><p>1.当INT32、INT64类型的值不为0时，FLOAT与DOUBLE类型的值不为0.0时，TEXT类型不为空字符串或者"false"时，转换为BOOLEAN类型时值为true，否则为false。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB> show timeseries root.sg.d1.*;
	+-------------+-----+-------------+--------+--------+-----------+----+----------+
	\| timeseries\|alias\| database\|dataType\|encoding\|compression\|tags\|attributes\|
	+-------------+-----+-------------+--------+--------+-----------+----+----------+
	\|root.sg.d1.s3\| null\| root.sg\| FLOAT\| RLE\| SNAPPY\|null\| null\|
	\|root.sg.d1.s4\| null\| root.sg\| DOUBLE\| RLE\| SNAPPY\|null\| null\|
	\|root.sg.d1.s5\| null\| root.sg\| TEXT\| PLAIN\| SNAPPY\|null\| null\|
	\|root.sg.d1.s6\| null\| root.sg\| BOOLEAN\| RLE\| SNAPPY\|null\| null\|
	\|root.sg.d1.s1\| null\| root.sg\| INT32\| RLE\| SNAPPY\|null\| null\|
	\|root.sg.d1.s2\| null\| root.sg\| INT64\| RLE\| SNAPPY\|null\| null\|
	+-------------+-----+-------------+--------+--------+-----------+----+----------+
	Total line number = 6
	It costs 0.006s
	IoTDB> select * from root.sg.d1;
	+-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
	\| Time\|root.sg.d1.s3\|root.sg.d1.s4\|root.sg.d1.s5\|root.sg.d1.s6\|root.sg.d1.s1\|root.sg.d1.s2\|
	+-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
	\|1970-01-01T08:00:00.001+08:00\| 1.1\| 1.1\| test\| false\| 1\| 1\|
	\|1970-01-01T08:00:00.002+08:00\| -2.2\| -2.2\| false\| true\| -2\| -2\|
	\|1970-01-01T08:00:00.003+08:00\| 0.0\| 0.0\| true\| true\| 0\| 0\|
	+-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
	Total line number = 3
	It costs 0.009s
	IoTDB> select cast(s1, 'type'='BOOLEAN'), cast(s2, 'type'='BOOLEAN'), cast(s3, 'type'='BOOLEAN'), cast(s4, 'type'='BOOLEAN'), cast(s5, 'type'='BOOLEAN') from root.sg.d1;
	+-----------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+
	\| Time\|cast(root.sg.d1.s1, "type"="BOOLEAN")\|cast(root.sg.d1.s2, "type"="BOOLEAN")\|cast(root.sg.d1.s3, "type"="BOOLEAN")\|cast(root.sg.d1.s4, "type"="BOOLEAN")\|cast(root.sg.d1.s5, "type"="BOOLEAN")\|
	+-----------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+
	\|1970-01-01T08:00:00.001+08:00\| true\| true\| true\| true\| true\|
	\|1970-01-01T08:00:00.002+08:00\| true\| true\| true\| true\| false\|
	\|1970-01-01T08:00:00.003+08:00\| false\| false\| false\| false\| true\|
	+-----------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+-------------------------------------+
	Total line number = 3
	It costs 0.012s
	</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>2.当BOOLEAN类型的值为true时，转换为INT32与INT64类型的值为1，转换为FLOAT或者DOUBLE类型时值为1.0，转换为TEXT类型时值为"true"。当BOOLEAN类型的值为false时，转换为INT32与INT64类型的值为0，转换为FLOAT或者DOUBLE类型时值为0.0，转换为TEXT类型时值为"false"。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB> select cast(s6, 'type'='INT32'), cast(s6, 'type'='INT64'), cast(s6, 'type'='FLOAT'), cast(s6, 'type'='DOUBLE'), cast(s6, 'type'='TEXT') from root.sg.d1;
	+-----------------------------+-----------------------------------+-----------------------------------+-----------------------------------+------------------------------------+----------------------------------+
	\| Time\|cast(root.sg.d1.s6, "type"="INT32")\|cast(root.sg.d1.s6, "type"="INT64")\|cast(root.sg.d1.s6, "type"="FLOAT")\|cast(root.sg.d1.s6, "type"="DOUBLE")\|cast(root.sg.d1.s6, "type"="TEXT")\|
	+-----------------------------+-----------------------------------+-----------------------------------+-----------------------------------+------------------------------------+----------------------------------+
	\|1970-01-01T08:00:00.001+08:00\| 0\| 0\| 0.0\| 0.0\| false\|
	\|1970-01-01T08:00:00.002+08:00\| 1\| 1\| 1.0\| 1.0\| true\|
	\|1970-01-01T08:00:00.003+08:00\| 1\| 1\| 1.0\| 1.0\| true\|
	+-----------------------------+-----------------------------------+-----------------------------------+-----------------------------------+------------------------------------+----------------------------------+
	Total line number = 3
	It costs 0.016s
	</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>3.当TEXT类型转换为INT32、INT64、FLOAT类型时，会先将TEXT类型的数据转换为DOUBLE类型，然后再转换为对应的类型，此时可能会存在损失精度的问题。如果无法转换的话则直接跳过。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB> select cast(s5, 'type'='INT32'), cast(s5, 'type'='INT64'), cast(s5, 'type'='FLOAT') from root.sg.d1;
	+----+-----------------------------------+-----------------------------------+-----------------------------------+
	\|Time\|cast(root.sg.d1.s5, "type"="INT32")\|cast(root.sg.d1.s5, "type"="INT64")\|cast(root.sg.d1.s5, "type"="FLOAT")\|
	+----+-----------------------------------+-----------------------------------+-----------------------------------+
	+----+-----------------------------------+-----------------------------------+-----------------------------------+
	Empty set.
	It costs 0.009s
	</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="使用示例" tabindex="-1"><a class="header-anchor" href="#使用示例"><span>使用示例</span></a></h3><p>测试数据：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB> select text from root.test;
	+-----------------------------+--------------+
	\| Time\|root.test.text\|
	+-----------------------------+--------------+
	\|1970-01-01T08:00:00.001+08:00\| 1.1\|
	\|1970-01-01T08:00:00.002+08:00\| 1\|
	\|1970-01-01T08:00:00.003+08:00\| hello world\|
	\|1970-01-01T08:00:00.004+08:00\| false\|
	+-----------------------------+--------------+
	</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>SQL语句：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'BOOLEAN'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'INT32'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'INT64'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'FLOAT'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cast<span class="token punctuation">(</span><span class="token keyword">text</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'DOUBLE'</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>test<span class="token punctuation">;</span>
	</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+--------------------------------------+------------------------------------+------------------------------------+------------------------------------+-------------------------------------+
	\| Time\|cast(root.test.text, "type"="BOOLEAN")\|cast(root.test.text, "type"="INT32")\|cast(root.test.text, "type"="INT64")\|cast(root.test.text, "type"="FLOAT")\|cast(root.test.text, "type"="DOUBLE")\|
	+-----------------------------+--------------------------------------+------------------------------------+------------------------------------+------------------------------------+-------------------------------------+
	\|1970-01-01T08:00:00.001+08:00\| true\| 1\| 1\| 1.1\| 1.1\|
	\|1970-01-01T08:00:00.002+08:00\| true\| 1\| 1\| 1.0\| 1.0\|
	\|1970-01-01T08:00:00.003+08:00\| true\| null\| null\| null\| null\|
	\|1970-01-01T08:00:00.004+08:00\| false\| null\| null\| null\| null\|
	+-----------------------------+--------------------------------------+------------------------------------+------------------------------------+------------------------------------+-------------------------------------+
	Total line number = 4
	It costs 0.078s
	</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,19),i=[o];function l(d,r){return s(),e("div",null,i)}const c=t(a,[["render",l],["__file","Conversion.html.vue"]]),p=JSON.parse('{"path":"/zh/UserGuide/V1.0.x/Operators-Functions/Conversion.html","title":"数据类型转换","lang":"zh-CN","frontmatter":{"description":"数据类型转换 CAST 函数简介当前IoTDB支持6种数据类型，其中包括INT32、INT64、FLOAT、DOUBLE、BOOLEAN以及TEXT。当我们对数据进行查询或者计算时可能需要进行数据类型的转换，比如说将TEXT转换为INT32，或者提高数据精度，比如说将FLOAT转换为DOUBLE。所以，IoTDB支持使用cast函数对数据类型进行转...","head":[["link",{"rel":"alternate","hreflang":"en-us","href":"https://iotdb.apache.org/UserGuide/V1.0.x/Operators-Functions/Conversion.html"}],["meta",{"property":"og:url","content":"https://iotdb.apache.org/zh/UserGuide/V1.0.x/Operators-Functions/Conversion.html"}],["meta",{"property":"og:site_name","content":"IoTDB Website"}],["meta",{"property":"og:title","content":"数据类型转换"}],["meta",{"property":"og:description","content":"数据类型转换 CAST 函数简介当前IoTDB支持6种数据类型，其中包括INT32、INT64、FLOAT、DOUBLE、BOOLEAN以及TEXT。当我们对数据进行查询或者计算时可能需要进行数据类型的转换，比如说将TEXT转换为INT32，或者提高数据精度，比如说将FLOAT转换为DOUBLE。所以，IoTDB支持使用cast函数对数据类型进行转..."}],["meta",{"property":"og:type","content":"article"}],["meta",{"property":"og:locale","content":"zh-CN"}],["meta",{"property":"og:locale:alternate","content":"en-US"}],["meta",{"property":"og:updated_time","content":"2023-07-10T03:11:17.000Z"}],["meta",{"property":"article:modified_time","content":"2023-07-10T03:11:17.000Z"}],["script",{"type":"application/ld+json"},"{\\"@context\\":\\"https://schema.org\\",\\"@type\\":\\"Article\\",\\"headline\\":\\"数据类型转换\\",\\"image\\":[\\"\\"],\\"dateModified\\":\\"2023-07-10T03:11:17.000Z\\",\\"author\\":[]}"]]},"headers":[{"level":2,"title":"CAST","slug":"cast","link":"#cast","children":[{"level":3,"title":"函数简介","slug":"函数简介","link":"#函数简介","children":[]},{"level":3,"title":"类型转换说明","slug":"类型转换说明","link":"#类型转换说明","children":[]},{"level":3,"title":"使用示例","slug":"使用示例","link":"#使用示例","children":[]}]}],"git":{"createdTime":1688958677000,"updatedTime":1688958677000,"contributors":[{"name":"CritasWang","email":"critas@outlook.com","commits":1}]},"readingTime":{"minutes":3.3,"words":989},"filePathRelative":"zh/UserGuide/V1.0.x/Operators-Functions/Conversion.md","localizedDate":"2023年7月10日","autoDesc":true}');export{c as comp,p as data};