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>
32 lines
5.4 KiB
HTML
32 lines
5.4 KiB
HTML
<a name="dli_08_0180"></a><a name="dli_08_0180"></a>
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<h1 class="topictitle1">AS for Table</h1>
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<div id="body8662426"><div class="section" id="dli_08_0180__en-us_topic_0093946999_s5dfe3200f50f470a96b0f6a2f98ada5b"><h4 class="sectiontitle">Function</h4><p id="dli_08_0180__en-us_topic_0093946999_a00d0ca88d3e3413c93b3fe2da6fb4046">This statement is used to specify an alias for a table or the subquery result.</p>
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<div class="section" id="dli_08_0180__en-us_topic_0093946999_se99c165d304f4772bde58334f3590471"><h4 class="sectiontitle">Syntax</h4><div class="codecoloring" codetype="Sql" id="dli_08_0180__screen13391131519438"><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_list</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">table_reference</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>
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</pre></div></td></tr></table></div>
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<div class="section" id="dli_08_0180__en-us_topic_0093946999_s05e823e1b4f94137a46936093ed7fca8"><h4 class="sectiontitle">Keyword</h4><ul id="dli_08_0180__en-us_topic_0093946999_u2f09e71d46494fc3a2a5f7e20a199d67"><li id="dli_08_0180__en-us_topic_0093946999_l25b1d340b5774ef49b67376265416a42">table_reference: Can be a table, view, or subquery.</li><li id="dli_08_0180__en-us_topic_0093946999_l9705e1392f8d4acb99ee6a9405481c04">As: Is used to connect to table_reference and alias. Whether this keyword is added or not does not affect the command execution result.</li></ul>
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<div class="section" id="dli_08_0180__en-us_topic_0093946999_s5f865082a4d9422f8214b290714c0a02"><h4 class="sectiontitle">Precautions</h4><ul id="dli_08_0180__en-us_topic_0093946999_u7ddc1857a56d4603b859119e86788fe7"><li id="dli_08_0180__en-us_topic_0093946999_l63f0561b10db46d89fb2e59c77d61625">The to-be-queried table must exist. Otherwise, an error is reported.</li><li id="dli_08_0180__en-us_topic_0093946999_l9101fe9c57bb465a8044ca0d3cd3c0c6">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>
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<div class="section" id="dli_08_0180__en-us_topic_0093946999_s6c6702bfdf85491baa5f52be4df3f670"><h4 class="sectiontitle">Example</h4><ul id="dli_08_0180__en-us_topic_0093946999_ul15229072155839"><li id="dli_08_0180__en-us_topic_0093946999_li514156155839">To specify alias <strong id="dli_08_0180__en-us_topic_0093946999_b842352706154829">n</strong> for table <strong id="dli_08_0180__en-us_topic_0093946999_b842352706154832">simple_table</strong> and visit the name field in table <strong id="dli_08_0180__en-us_topic_0093946999_b84235270615492">simple_table</strong> by using n.name, run the following statement:<div class="codecoloring" codetype="Sql" id="dli_08_0180__screen25953377430"><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="p">.</span><span class="n">score</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="n">n</span><span class="w"> </span><span class="k">WHERE</span><span class="w"> </span><span class="n">n</span><span class="p">.</span><span class="n">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">"leilei"</span><span class="p">;</span>
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</pre></div></td></tr></table></div>
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</div>
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</li><li id="dli_08_0180__en-us_topic_0093946999_li47917187155839">To specify alias <strong id="dli_08_0180__en-us_topic_0093946999_b842352706154923">m</strong> for the subquery result and return all the query results using <strong id="dli_08_0180__en-us_topic_0093946999_b842352706154938">SELECT * FROM m</strong>, run the following statement:<div class="codecoloring" codetype="Sql" id="dli_08_0180__screen188674490435"><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="o">*</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="o">*</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="k">AS</span><span class="w"> </span><span class="n">m</span><span class="p">;</span>
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</pre></div></td></tr></table></div>
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</div>
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</li></ul>
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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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