forked from docs/doc-exports
Su, Xiaomeng
04d4597cf3
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>
28 lines
4.5 KiB
HTML
28 lines
4.5 KiB
HTML
<a name="dli_08_0181"></a><a name="dli_08_0181"></a>
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<h1 class="topictitle1">AS for Column</h1>
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<div id="body8662426"><div class="section" id="dli_08_0181__en-us_topic_0093946749_s73db924bee2d4ca188d0696d7238963d"><h4 class="sectiontitle">Function</h4><p id="dli_08_0181__en-us_topic_0093946749_a910483a40aad45ee928b811dac51b40e">This statement is used to specify an alias for a column. </p>
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<div class="section" id="dli_08_0181__en-us_topic_0093946749_s3f19fad07d334b87938d2b394c055b93"><h4 class="sectiontitle">Syntax</h4><div class="codecoloring" codetype="Sql" id="dli_08_0181__screen191961835443"><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="k">SELECT</span><span class="w"> </span><span class="n">attr_expr</span><span class="w"> </span><span class="p">[</span><span class="k">AS</span><span class="p">]</span><span class="w"> </span><span class="k">alias</span><span class="p">,</span><span class="w"> </span><span class="n">attr_expr</span><span class="w"> </span><span class="p">[</span><span class="k">AS</span><span class="p">]</span><span class="w"> </span><span class="k">alias</span><span class="p">,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">table_reference</span><span class="p">;</span>
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</pre></div></td></tr></table></div>
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<div class="section" id="dli_08_0181__en-us_topic_0093946749_sfbe032ee197641959ec93d92e091a1db"><h4 class="sectiontitle">Keyword</h4><ul id="dli_08_0181__en-us_topic_0093946749_ufca046cdf32f433ebc6380010bec5666"><li id="dli_08_0181__en-us_topic_0093946749_l08122ed20bf44ef49d9a05b40d370f56">alias: gives an alias for the <strong id="dli_08_0181__b3268416173411">attr_expr</strong> field.</li><li id="dli_08_0181__en-us_topic_0093946749_ld2780bd7a2bc4863aa8ea2aaaf250d03">AS: Whether to add AS does not affect the result.</li></ul>
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<div class="section" id="dli_08_0181__en-us_topic_0093946749_sec59ae930c284dbdb60df66835547f39"><h4 class="sectiontitle">Precautions</h4><ul id="dli_08_0181__en-us_topic_0093946749_u686fe58be99f48569f3e41cf3062acbe"><li id="dli_08_0181__en-us_topic_0093946749_la1a7db79e80c495caf6b55a8bdb4019e">The to-be-queried table must exist. Otherwise, an error is reported.</li><li id="dli_08_0181__en-us_topic_0093946749_ld6544f9247364b51abdbf895563ed276">The alias must be specified before execution of the statement. Otherwise, an error is reported. You are advised to specify a unique alias.</li></ul>
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<div class="section" id="dli_08_0181__en-us_topic_0093946749_sedf9feac5e074a75be1be6e9f55201fd"><h4 class="sectiontitle">Example</h4><p id="dli_08_0181__en-us_topic_0093946749_ad4204544f9124affad7b7d4c2741b391">Run <strong id="dli_08_0181__b12266592356">SELECT name AS n FROM simple_table WHERE score > 90</strong> to obtain the subquery result. The alias <strong id="dli_08_0181__b18818143193619">n</strong> for <strong id="dli_08_0181__b48531737133615">name</strong> can be used by external SELECT statement. </p>
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<div class="codecoloring" codetype="Sql" id="dli_08_0181__screen111115178448"><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="k">SELECT</span><span class="w"> </span><span class="n">n</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="p">(</span><span class="k">SELECT</span><span class="w"> </span><span class="n">name</span><span class="w"> </span><span class="k">AS</span><span class="w"> </span><span class="n">n</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">simple_table</span><span class="w"> </span><span class="k">WHERE</span><span class="w"> </span><span class="n">score</span><span class="w"> </span><span class="o">></span><span class="w"> </span><span class="mi">90</span><span class="p">)</span><span class="w"> </span><span class="n">m</span><span class="w"> </span><span class="k">WHERE</span><span class="w"> </span><span class="n">n</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">"xiaoming"</span><span class="p">;</span>
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</pre></div></td></tr></table></div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dli_08_0179.html">Alias</a></div>
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