vpruthi/doc-exports
1
0
Fork 0
forked from docs/doc-exports
Code Pull Requests Activity
doc-exports/docs/dws/dev/dws_06_0070.html
Lu, Huayi ef0ada5a59 DWS DEV 20240716 version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2024-11-02 09:07:47 +00:00

146 lines
13 KiB
HTML
Raw Blame History

<a name="EN-US_TOPIC_0000001460561476"></a><a name="EN-US_TOPIC_0000001460561476"></a>
<h1 class="topictitle1">Simple Expressions</h1>
<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001460561476__sf77bb627053b43558147ac5663658a52"><h4 class="sectiontitle">Logical Expressions</h4><p id="EN-US_TOPIC_0000001460561476__ac0ed512120fa4b2a86dd1a6ee7e0dd6f"><a href="dws_06_0028.html">Logical Operators</a> lists the operators and calculation rules of logical expressions.</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001460561476__s5dbd3d36dfe54b9abd38075cc957a05d"><h4 class="sectiontitle">Comparative Expressions</h4><p id="EN-US_TOPIC_0000001460561476__ade6d51db1ee348979babe2451a2ef09d"><a href="dws_06_0029.html">Comparison Operators</a> lists the common comparative operators.</p>
<p id="EN-US_TOPIC_0000001460561476__a1aabddb870774dcf8c325200e7cccdb0">In addition to comparative operators, you can also use the following sentence structure:</p>
<ul id="EN-US_TOPIC_0000001460561476__u377bbd2082b44778b3a7e20d6b654e19"><li id="EN-US_TOPIC_0000001460561476__lccb4a3855aff47d7a5c90a91277056e2">BETWEEN operator<p id="EN-US_TOPIC_0000001460561476__accbbe0acbb52443282df25346eb975e9"><a name="EN-US_TOPIC_0000001460561476__lccb4a3855aff47d7a5c90a91277056e2"></a><a name="lccb4a3855aff47d7a5c90a91277056e2"></a><strong id="EN-US_TOPIC_0000001460561476__b84235270620354">a BETWEEN x<em id="EN-US_TOPIC_0000001460561476__i136301522020352"> </em> AND y</strong> is equivalent to <strong id="EN-US_TOPIC_0000001460561476__b84235270620358">a &gt;= x AND a &lt;= y</strong>.</p>
<p id="EN-US_TOPIC_0000001460561476__a8c519a4bf34847b089491f0114297b78"><strong id="EN-US_TOPIC_0000001460561476__b8423527062047">a NOT BETWEEN<em id="EN-US_TOPIC_0000001460561476__i67082715"></em> x AND y</strong> is equivalent to <strong id="EN-US_TOPIC_0000001460561476__b84235270620414">a &lt; x OR a &gt; y</strong>.</p>
</li><li id="EN-US_TOPIC_0000001460561476__l7ed425bdcb374e62ab2d39c9021b1a94">To check whether a value is null, use:<p id="EN-US_TOPIC_0000001460561476__ac3ce0b9487a84173b188a1587e1d9971"><a name="EN-US_TOPIC_0000001460561476__l7ed425bdcb374e62ab2d39c9021b1a94"></a><a name="l7ed425bdcb374e62ab2d39c9021b1a94"></a>expression<em id="EN-US_TOPIC_0000001460561476__a4ec5e963903446feae8ebe82b2a3914c"> </em>IS NULL</p>
<p id="EN-US_TOPIC_0000001460561476__a779e14aa202d45178723dd692c0c1b6e">expression IS NOT NULL</p>
<p id="EN-US_TOPIC_0000001460561476__a0ffa5775a4a44c34a6570f74151ebb02">or an equivalent (non-standard) sentence structure:</p>
<p id="EN-US_TOPIC_0000001460561476__ad530f0510c5340f69ce7ef4752387ca2">expression<em id="EN-US_TOPIC_0000001460561476__ad179abd144474337a947e36cee612d7f"> </em> ISNULL</p>
<p id="EN-US_TOPIC_0000001460561476__a92428f5bcfd7423295e6fa00e259f030">expression NOTNULL</p>
<div class="notice" id="EN-US_TOPIC_0000001460561476__nc239e25e72a14c40b08f7ac5186c0d3b"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001460561476__a43641f7201624ae0a2687020ea2abae0">Do not write <strong id="EN-US_TOPIC_0000001460561476__b52414719510">expression=NULL</strong> or <strong id="EN-US_TOPIC_0000001460561476__b122604410517">expression&lt;&gt;(!=)NULL</strong>, because <strong id="EN-US_TOPIC_0000001460561476__b62141141345">NULL</strong> represents an unknown value, and these expressions cannot determine whether two unknown values are equal.</p>
</div></div>
</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001460561476__sfb3ab75064b74cb68be60b6edc0df956"><h4 class="sectiontitle">Examples</h4><div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001460561476__s046c391830114f76840e5ad5e8c4742c"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span>
<span class="normal">15</span>
<span class="normal">16</span>
<span class="normal">17</span>
<span class="normal">18</span>
<span class="normal">19</span>
<span class="normal">20</span>
<span class="normal">21</span>
<span class="normal">22</span>
<span class="normal">23</span>
<span class="normal">24</span>
<span class="normal">25</span>
<span class="normal">26</span>
<span class="normal">27</span>
<span class="normal">28</span>
<span class="normal">29</span>
<span class="normal">30</span>
<span class="normal">31</span>
<span class="normal">32</span>
<span class="normal">33</span>
<span class="normal">34</span>
<span class="normal">35</span>
<span class="normal">36</span>
<span class="normal">37</span>
<span class="normal">38</span>
<span class="normal">39</span>
<span class="normal">40</span>
<span class="normal">41</span>
<span class="normal">42</span>
<span class="normal">43</span>
<span class="normal">44</span>
<span class="normal">45</span>
<span class="normal">46</span>
<span class="normal">47</span>
<span class="normal">48</span>
<span class="normal">49</span>
<span class="normal">50</span>
<span class="normal">51</span>
<span class="normal">52</span>
<span class="normal">53</span>
<span class="normal">54</span>
<span class="normal">55</span>
<span class="normal">56</span>
<span class="normal">57</span>
<span class="normal">58</span>
<span class="normal">59</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">BETWEEN</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">AND</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">AND</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">BETWEEN</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">AND</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">f</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">OR</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">f</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="o">+</span><span class="mi">2</span><span class="w"> </span><span class="k">IS</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">f</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="o">+</span><span class="mi">2</span><span class="w"> </span><span class="k">IS</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="o">+</span><span class="mi">2</span><span class="w"> </span><span class="k">ISNULL</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">f</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="o">+</span><span class="mi">2</span><span class="w"> </span><span class="k">NOTNULL</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="o">+</span><span class="mi">2</span><span class="w"> </span><span class="k">IS</span><span class="w"> </span><span class="k">DISTINCT</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
<span class="k">SELECT</span><span class="w"> </span><span class="mi">2</span><span class="o">+</span><span class="mi">2</span><span class="w"> </span><span class="k">IS</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">DISTINCT</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="k">RESULT</span><span class="p">;</span>
<span class="w"> </span><span class="k">result</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">f</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_06_0069.html">Expressions</a></div>
</div>
</div>
View Git Blame Copy Permalink