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luhuayi
a5e3903f6b
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: luhuayi <luhuayi@huawei.com> Co-committed-by: luhuayi <luhuayi@huawei.com>
96 lines
16 KiB
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96 lines
16 KiB
HTML
<a name="EN-US_TOPIC_0000001860198981"></a><a name="EN-US_TOPIC_0000001860198981"></a>
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<h1 class="topictitle1">SET|DROP COLUMN DEFAULT VALUE</h1>
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<div id="body8662426"><p id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_p19751438112911">In MySQL, the <strong id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_b188609333541">COLUMN</strong> keyword can be omitted when the <strong id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_b786010335546">ALTER</strong> statement is used to set the default value of a column. DSC will perform adaptation based on GaussDB(DWS) features during migration.</p>
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<p id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_p8060118"><strong id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_b20727929204011">Input</strong></p>
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<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_screen173026529304"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
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<span class="normal"> 2</span>
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<span class="normal"> 3</span>
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<span class="normal"> 4</span>
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<span class="normal"> 5</span>
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<span class="normal"> 6</span>
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<span class="normal"> 7</span>
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<span class="normal"> 8</span>
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<span class="normal"> 9</span>
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<span class="normal">10</span>
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<span class="normal">11</span>
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<span class="normal">12</span>
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<span class="normal">13</span>
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<span class="normal">14</span>
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<span class="normal">15</span>
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<span class="normal">16</span>
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<span class="normal">17</span>
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<span class="normal">18</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="o">`</span><span class="n">runoob_alter_test</span><span class="o">`</span><span class="p">(</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType1</span><span class="o">`</span><span class="w"> </span><span class="nb">int</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="n">AUTO_INCREMENT</span><span class="p">,</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType2</span><span class="o">`</span><span class="w"> </span><span class="nb">FLOAT</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="mi">2</span><span class="p">),</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType3</span><span class="o">`</span><span class="w"> </span><span class="n">DOUBLE</span><span class="p">(</span><span class="mi">20</span><span class="p">,</span><span class="mi">8</span><span class="p">),</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType4</span><span class="o">`</span><span class="w"> </span><span class="nb">TEXT</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType5</span><span class="o">`</span><span class="w"> </span><span class="k">YEAR</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">DEFAULT</span><span class="w"> </span><span class="s1">'2018'</span><span class="p">,</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType6</span><span class="o">`</span><span class="w"> </span><span class="n">DATETIME</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">DEFAULT</span><span class="w"> </span><span class="s1">'2018-10-12 15:27:33.999999'</span><span class="p">,</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType7</span><span class="o">`</span><span class="w"> </span><span class="nb">CHAR</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">DEFAULT</span><span class="w"> </span><span class="s1">''</span><span class="p">,</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType8</span><span class="o">`</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">50</span><span class="p">),</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType9</span><span class="o">`</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">50</span><span class="p">)</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">DEFAULT</span><span class="w"> </span><span class="s1">''</span><span class="p">,</span>
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<span class="w"> </span><span class="o">`</span><span class="n">dataType10</span><span class="o">`</span><span class="w"> </span><span class="k">TIME</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">DEFAULT</span><span class="w"> </span><span class="s1">'10:20:59'</span><span class="p">,</span>
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<span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="p">(</span><span class="o">`</span><span class="n">dataType1</span><span class="o">`</span><span class="p">)</span>
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<span class="p">)</span><span class="n">ENGINE</span><span class="o">=</span><span class="n">InnoDB</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="n">CHARSET</span><span class="o">=</span><span class="n">utf8</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">runoob_alter_test</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="n">dataType2</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">runoob_alter_test</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="n">dataType2</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">runoob_alter_test</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="n">dataType2</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">DEFAULT</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">runoob_alter_test</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="n">dataType2</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">DEFAULT</span><span class="p">;</span>
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</pre></div></td></tr></table></div>
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</div>
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<p id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_p1431826173714"><strong id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_b11199142516406">Output</strong></p>
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<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001860198981__en-us_topic_0000001435815993_en-us_topic_0214164473_screen18665125423015"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
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<span class="normal"> 2</span>
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<span class="normal"> 3</span>
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<span class="normal"> 4</span>
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<span class="normal"> 5</span>
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<span class="normal"> 6</span>
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<span class="normal"> 7</span>
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<span class="normal"> 8</span>
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<span class="normal"> 9</span>
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<span class="normal">10</span>
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<span class="normal">11</span>
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<span class="normal">12</span>
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<span class="normal">13</span>
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<span class="normal">14</span>
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<span class="normal">15</span>
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<span class="normal">16</span>
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<span class="normal">17</span>
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<span class="normal">18</span>
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<span class="normal">19</span>
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<span class="normal">20</span>
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<span class="normal">21</span>
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<span class="normal">22</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="ss">"public"</span><span class="p">.</span><span class="ss">"runoob_alter_test"</span>
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<span class="p">(</span>
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<span class="w"> </span><span class="ss">"datatype1"</span><span class="w"> </span><span class="nb">SERIAL</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype2"</span><span class="w"> </span><span class="nb">REAL</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype3"</span><span class="w"> </span><span class="n">DOUBLE</span><span class="w"> </span><span class="k">PRECISION</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype4"</span><span class="w"> </span><span class="nb">TEXT</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype5"</span><span class="w"> </span><span class="nb">SMALLINT</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">DEFAULT</span><span class="w"> </span><span class="s1">'2018'</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype6"</span><span class="w"> </span><span class="k">TIMESTAMP</span><span class="w"> </span><span class="k">WITHOUT</span><span class="w"> </span><span class="k">TIME</span><span class="w"> </span><span class="k">ZONE</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">DEFAULT</span><span class="w"> </span><span class="s1">'2018-10-12 15:27:33.999999'</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype7"</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">4</span><span class="p">)</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">DEFAULT</span><span class="w"> </span><span class="s1">''</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype8"</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">200</span><span class="p">),</span>
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<span class="w"> </span><span class="ss">"datatype9"</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">200</span><span class="p">)</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">DEFAULT</span><span class="w"> </span><span class="s1">''</span><span class="p">,</span>
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<span class="w"> </span><span class="ss">"datatype10"</span><span class="w"> </span><span class="k">TIME</span><span class="w"> </span><span class="k">WITHOUT</span><span class="w"> </span><span class="k">TIME</span><span class="w"> </span><span class="k">ZONE</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">DEFAULT</span><span class="w"> </span><span class="s1">'10:20:59'</span><span class="p">,</span>
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<span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="p">(</span><span class="ss">"datatype1"</span><span class="p">)</span>
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<span class="p">)</span>
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<span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">ORIENTATION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">ROW</span><span class="p">,</span><span class="w"> </span><span class="n">COMPRESSION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">NO</span><span class="w"> </span><span class="p">)</span>
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<span class="w"> </span><span class="n">NOCOMPRESS</span>
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<span class="w"> </span><span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">HASH</span><span class="w"> </span><span class="p">(</span><span class="ss">"datatype1"</span><span class="p">);</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="ss">"public"</span><span class="p">.</span><span class="ss">"runoob_alter_test"</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="ss">"datatype2"</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="s1">'1'</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="ss">"public"</span><span class="p">.</span><span class="ss">"runoob_alter_test"</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="ss">"datatype2"</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="s1">'3'</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="ss">"public"</span><span class="p">.</span><span class="ss">"runoob_alter_test"</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="ss">"datatype2"</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">DEFAULT</span><span class="p">;</span>
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<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="ss">"public"</span><span class="p">.</span><span class="ss">"runoob_alter_test"</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="ss">"datatype2"</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">DEFAULT</span><span class="p">;</span>
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</pre></div></td></tr></table></div>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_16_0119.html">Table (Optional Parameters and Operations)</a></div>
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</div>
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</div>
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