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import{_ as e,C as t,O as o,P as i,ah as p,Q as l,U as s,ai as c,ae as r,aW as n}from"./framework-62ad666a.js";const d={},u=n(`<h1 id="literal-values" tabindex="-1"><a class="header-anchor" href="#literal-values" aria-hidden="true">#</a> Literal Values</h1><p>This section describes how to write literal values in IoTDB. These include strings, numbers, timestamp values, boolean values, and NULL.</p><h2 id="string-literals" tabindex="-1"><a class="header-anchor" href="#string-literals" aria-hidden="true">#</a> String Literals</h2><p>in IoTDB, <strong>A string is a sequence of bytes or characters, enclosed within either single quote (<code>&#39;</code>) or double quote (<code>&quot;</code>) characters.</strong> Examples：</p><div class="language-javascript line-numbers-mode" data-ext="js"><pre class="language-javascript"><code><span class="token string">&#39;a string&#39;</span>
<span class="token string">&quot;another string&quot;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="usage-scenarios" tabindex="-1"><a class="header-anchor" href="#usage-scenarios" aria-hidden="true">#</a> Usage Scenarios</h3><p>Usages of string literals:</p><ul><li><p>Values of <code>TEXT</code> type data in <code>INSERT</code> or <code>SELECT</code> statements</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># insert</span>
<span class="token keyword">insert</span> <span class="token keyword">into</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf02<span class="token punctuation">.</span>wt02<span class="token punctuation">(</span><span class="token keyword">timestamp</span><span class="token punctuation">,</span>hardware<span class="token punctuation">)</span> <span class="token keyword">values</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token string">&#39;v1&#39;</span><span class="token punctuation">)</span>
<span class="token keyword">insert</span> <span class="token keyword">into</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf02<span class="token punctuation">.</span>wt02<span class="token punctuation">(</span><span class="token keyword">timestamp</span><span class="token punctuation">,</span>hardware<span class="token punctuation">)</span> <span class="token keyword">values</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token string">&#39;\\\\&#39;</span><span class="token punctuation">)</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+--------------------------+</span>
<span class="token operator">|</span> <span class="token keyword">Time</span><span class="token operator">|</span>root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf02<span class="token punctuation">.</span>wt02<span class="token punctuation">.</span>hardware<span class="token operator">|</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+--------------------------+</span>
<span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.001</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> v1<span class="token operator">|</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+--------------------------+</span>
<span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.002</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> \\\\<span class="token operator">|</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+--------------------------+</span>
<span class="token comment"># select</span>
<span class="token keyword">select</span> code <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg1<span class="token punctuation">.</span>d1 <span class="token keyword">where</span> code <span class="token operator">in</span> <span class="token punctuation">(</span><span class="token string">&#39;string1&#39;</span><span class="token punctuation">,</span> <span class="token string">&#39;string2&#39;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</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></div></li><li><p>Used in<code>LOAD</code> / <code>REMOVE</code> / <code>SETTLE</code> instructions to represent file path.</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># load</span>
<span class="token keyword">LOAD</span> <span class="token string">&#39;examplePath&#39;</span>
<span class="token comment"># remove</span>
REMOVE <span class="token string">&#39;examplePath&#39;</span>
<span class="token comment"># SETTLE</span>
SETTLE <span class="token string">&#39;examplePath&#39;</span>
</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></div></li><li><p>Password fields in user management statements</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># write_pwd is the password</span>
<span class="token keyword">CREATE</span> <span class="token keyword">USER</span> ln_write_user <span class="token string">&#39;write_pwd&#39;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>Full Java class names in UDF and trigger management statements</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># Trigger example. Full java class names after &#39;AS&#39; should be string literals.</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TRIGGER</span> <span class="token identifier"><span class="token punctuation">\`</span>alert-listener-sg1d1s1<span class="token punctuation">\`</span></span>
<span class="token keyword">AFTER</span> <span class="token keyword">INSERT</span>
<span class="token keyword">ON</span> root<span class="token punctuation">.</span>sg1<span class="token punctuation">.</span>d1<span class="token punctuation">.</span>s1
<span class="token keyword">AS</span> <span class="token string">&#39;org.apache.iotdb.db.engine.trigger.example.AlertListener&#39;</span>
<span class="token keyword">WITH</span> <span class="token punctuation">(</span>
<span class="token string">&#39;lo&#39;</span> <span class="token operator">=</span> <span class="token string">&#39;0&#39;</span><span class="token punctuation">,</span>
<span class="token string">&#39;hi&#39;</span> <span class="token operator">=</span> <span class="token string">&#39;100.0&#39;</span>
<span class="token punctuation">)</span>
<span class="token comment"># UDF example. Full java class names after &#39;AS&#39; should be string literals.</span>
<span class="token keyword">CREATE</span> <span class="token keyword">FUNCTION</span> example <span class="token keyword">AS</span> <span class="token string">&#39;org.apache.iotdb.udf.UDTFExample&#39;</span>
</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></div></li><li><p><code>AS</code> function provided by IoTDB can assign an alias to time series selected in query. Alias can be constant(including string) or identifier.</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> s1 <span class="token keyword">as</span> <span class="token string">&#39;temperature&#39;</span><span class="token punctuation">,</span> s2 <span class="token keyword">as</span> <span class="token string">&#39;speed&#39;</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span>
<span class="token comment"># Header of dataset</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+-----------|-----+</span>
<span class="token operator">|</span> <span class="token keyword">Time</span><span class="token operator">|</span>temperature<span class="token operator">|</span>speed<span class="token operator">|</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+-----------|-----+</span>
</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></div></li><li><p>The key/value of an attribute can be String Literal and identifier, more details can be found at <strong>key-value pair</strong> part.</p></li></ul><h3 id="how-to-use-quotation-marks-in-string-literals" tabindex="-1"><a class="header-anchor" href="#how-to-use-quotation-marks-in-string-literals" aria-hidden="true">#</a> How to use quotation marks in String Literals</h3><p>There are several ways to include quote characters within a string:</p><ul><li><code>&#39;</code> inside a string quoted with <code>&quot;</code> needs no special treatment and need not be doubled or escaped. In the same way, <code>&quot;</code> inside a string quoted with <code>&#39;</code> needs no special treatment.</li><li>A <code>&#39;</code> inside a string quoted with <code>&#39;</code> may be written as <code>&#39;&#39;</code>.</li><li>A <code>&quot;</code> inside a string quoted with <code>&quot;</code> may be written as <code>&quot;&quot;</code>.</li></ul><p>The following examples demonstrate how quoting and escaping work:</p><div class="language-javascript line-numbers-mode" data-ext="js"><pre class="language-javascript"><code><span class="token string">&#39;string&#39;</span> <span class="token comment">// string</span>
<span class="token string">&#39;&quot;string&quot;&#39;</span> <span class="token comment">// &quot;string&quot;</span>
<span class="token string">&#39;&quot;&quot;string&quot;&quot;&#39;</span> <span class="token comment">// &quot;&quot;string&quot;&quot;</span>
<span class="token string">&#39;&#39;</span><span class="token string">&#39;string&#39;</span> <span class="token comment">// &#39;string</span>
<span class="token string">&quot;string&quot;</span> <span class="token comment">// string</span>
<span class="token string">&quot;&#39;string&#39;&quot;</span> <span class="token comment">// &#39;string&#39;</span>
<span class="token string">&quot;&#39;&#39;string&#39;&#39;&quot;</span> <span class="token comment">// &#39;&#39;string&#39;&#39;</span>
<span class="token string">&quot;&quot;</span><span class="token string">&quot;string&quot;</span> <span class="token comment">// &quot;string</span>
</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><h2 id="numeric-literals" tabindex="-1"><a class="header-anchor" href="#numeric-literals" aria-hidden="true">#</a> Numeric Literals</h2><p>Number literals include integer (exact-value) literals and floating-point (approximate-value) literals.</p><p>Integers are represented as a sequence of digits. Numbers may be preceded by <code>-</code> or <code>+</code> to indicate a negative or positive value, respectively. Examples: <code>1</code>, <code>-1</code>.</p><p>Numbers with fractional part or represented in scientific notation with a mantissa and exponent are approximate-value numbers. Examples: <code>.1</code>, <code>3.14</code>, <code>-2.23</code>, <code>+1.70</code>, <code>1.2E3</code>, <code>1.2E-3</code>, <code>-1.2E3</code>, <code>-1.2E-3</code>.</p><p>The <code>INT32</code> and <code>INT64</code> data types are integer types and calculations are exact.</p><p>The <code>FLOAT</code> and <code>DOUBLE</code> data types are floating-point types and calculations are approximate.</p><p>An integer may be used in floating-point context; it is interpreted as the equivalent floating-point number.</p><h2 id="timestamp-literals" tabindex="-1"><a class="header-anchor" href="#timestamp-literals" aria-hidden="true">#</a> Timestamp Literals</h2>`,21),m=n('<p>Specially, <code>NOW()</code> represents a constant timestamp that indicates the system time at which the statement began to execute.</p><h2 id="boolean-literals" tabindex="-1"><a class="header-anchor" href="#boolean-literals" aria-hidden="true">#</a> Boolean Literals</h2><p>The constants <code>TRUE</code> and <code>FALSE</code> evaluate to 1 and 0, respectively. The constant names can be written in any lettercase.</p><h2 id="null-values" tabindex="-1"><a class="header-anchor" href="#null-values" aria-hidden="true">#</a> NULL Values</h2><p>The <code>NULL</code> value means “no data.” <code>NULL</code> can be written in any lettercase.</p>',5);function k(v,g){const a=t("RouterLink");return o(),i("div",null,[p(`
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