vpruthi/doc-exports
1
0
Fork 0
forked from docs/doc-exports
Code Pull Requests Activity
doc-exports/docs/dli/sqlreference/dli_08_0323.html
Su, Xiaomeng 04d4597cf3 dli_sqlreference_0511_version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Su, Xiaomeng <suxiaomeng1@huawei.com>
Co-committed-by: Su, Xiaomeng <suxiaomeng1@huawei.com>
2023-11-02 14:34:08 +00:00

57 lines
10 KiB
HTML
Raw Blame History

<a name="dli_08_0323"></a><a name="dli_08_0323"></a>
<h1 class="topictitle1">Set Operations</h1>
<div id="body8662426"><div class="section" id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_section1111420567382"><h4 class="sectiontitle">UNION/UNION ALL/INTERSECT/EXCEPT</h4><p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p16759811113919"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b164693580255">Syntax</strong></p>
<div class="codecoloring" codetype="Sql" id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0102_screen1883416446284"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="n">query</span><span class="w"> </span><span class="k">UNION</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">ALL</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">Intersect</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">Except</span><span class="w"> </span><span class="n">query</span>
</pre></div></td></tr></table></div>
</div>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p137251811113911"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b13460191202618">Description</strong></p>
<ul id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_ul19923610158"><li id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_li1999436171517">UNION is used to return the union set of multiple query results.</li><li id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_li20746237121512">INTERSECT is used to return the intersection of multiple query results.</li><li id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_li874810520151">EXCEPT is used to return the difference set of multiple query results.</li></ul>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p137018116393"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b94614692618">Precautions</strong></p>
<ul id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_u2da4760a69164fb092c1fce01777d7b4"><li id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0102_l735e1588d3af4b7bb68819a7c778082d">Set operation is to join tables from head to tail under certain conditions. The quantity of columns returned by each SELECT statement must be the same. Column types must be the same. Column names can be different.</li><li id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0102_li888434620323">By default, the duplicate records returned by UNION are removed. The duplicate records returned by UNION ALL are not removed.</li></ul>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p11683101110392"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b3914191252611">Example</strong></p>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0102_p1755688193218">Output the union set of Orders1 and Orders2 without duplicate records.</p>
<div class="codecoloring" codetype="Sql" id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0102_screen1246412277337"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">insert</span><span class="w"> </span><span class="k">into</span><span class="w"> </span><span class="n">temp</span><span class="w"> </span><span class="k">SELECT</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">Orders1</span>
<span class="w"> </span><span class="k">UNION</span><span class="w"> </span><span class="k">SELECT</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">Orders2</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_section135840332392"><h4 class="sectiontitle">IN</h4><p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p187182598392"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b115021819132611">Syntax</strong></p>
<div class="codecoloring" codetype="Sql" id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_screen62530710320"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">ALL</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DISTINCT</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">projectItem</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="n">projectItem</span><span class="w"> </span><span class="p">]</span><span class="o">*</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">tableExpression</span>
<span class="w"> </span><span class="k">WHERE</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">IN</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="w"> </span><span class="p">(,</span><span class="w"> </span><span class="n">value</span><span class="p">)</span><span class="o">*</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">query</span>
</pre></div></td></tr></table></div>
</div>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p12698195943913"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b662132192620">Description</strong></p>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_a26520665670f45d190e2ad266a7e6158">The IN operator allows multiple values to be specified in the WHERE clause. It returns true if the expression exists in the given table subquery.</p>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p126811059143919"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b1299132416261">Precautions</strong></p>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_p56557216166">The subquery table must consist of a single column, and the data type of the column must be the same as that of the expression.</p>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_p466416593391"><strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_b76022682616">Example</strong></p>
<p id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_a132e15af42c342a0bb9c96b295011979">Return <strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_b17892164931014">user</strong> and <strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_b2053385113107">amount</strong> information of the products in <strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_b196941323111117">NewProducts</strong> of the <strong id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_b17257043103814">Orders</strong> table.</p>
<div class="codecoloring" codetype="Sql" id="dli_08_0323__en-us_topic_0000001119072202_en-us_topic_0000001127976907_dli_08_0103_s41849cfb7da54a76ab8b64216b4c4218"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">insert</span><span class="w"> </span><span class="k">into</span><span class="w"> </span><span class="n">temp</span><span class="w"> </span><span class="k">SELECT</span><span class="w"> </span><span class="k">user</span><span class="p">,</span><span class="w"> </span><span class="n">amount</span>
<span class="k">FROM</span><span class="w"> </span><span class="n">Orders</span>
<span class="k">WHERE</span><span class="w"> </span><span class="n">product</span><span class="w"> </span><span class="k">IN</span><span class="w"> </span><span class="p">(</span>
<span class="w"> </span><span class="k">SELECT</span><span class="w"> </span><span class="n">product</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">NewProducts</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="dli_08_0321.html">Data Manipulation Language (DML)</a></div>
</div>
</div>
View Git Blame Copy Permalink