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Lu, Huayi e6fa411af0 DWS DEV 830.201 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>
2024-05-16 07:24:04 +00:00

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<a name="EN-US_TOPIC_0000001628021390"></a><a name="EN-US_TOPIC_0000001628021390"></a>
<h1 class="topictitle1">Querying a Single Table</h1>
<div id="body0000001628021390"><p id="EN-US_TOPIC_0000001628021390__p11185944114919">Example table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001628021390__screen124541238204913"><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></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="n">newproducts</span>
<span class="p">(</span>
<span class="n">product_id</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
<span class="n">product_name</span><span class="w"> </span><span class="n">VARCHAR2</span><span class="p">(</span><span class="mi">60</span><span class="p">),</span>
<span class="n">category</span><span class="w"> </span><span class="n">VARCHAR2</span><span class="p">(</span><span class="mi">60</span><span class="p">),</span>
<span class="n">quantity</span><span class="w"> </span><span class="nb">INTEGER</span>
<span class="p">)</span>
<span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="n">ORIENTATION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">COLUMN</span><span class="p">)</span><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="p">(</span><span class="n">product_id</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">1502</span><span class="p">,</span><span class="w"> </span><span class="s1">'earphones'</span><span class="p">,</span><span class="w"> </span><span class="s1">'electronics'</span><span class="p">,</span><span class="mi">150</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">1601</span><span class="p">,</span><span class="w"> </span><span class="s1">'telescope'</span><span class="p">,</span><span class="w"> </span><span class="s1">'toys'</span><span class="p">,</span><span class="mi">80</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">1666</span><span class="p">,</span><span class="w"> </span><span class="s1">'Frisbee'</span><span class="p">,</span><span class="w"> </span><span class="s1">'toys'</span><span class="p">,</span><span class="mi">244</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">1700</span><span class="p">,</span><span class="w"> </span><span class="s1">'interface'</span><span class="p">,</span><span class="w"> </span><span class="s1">'books'</span><span class="p">,</span><span class="mi">100</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">2344</span><span class="p">,</span><span class="w"> </span><span class="s1">'milklotion'</span><span class="p">,</span><span class="w"> </span><span class="s1">'skin care'</span><span class="p">,</span><span class="mi">320</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">3577</span><span class="p">,</span><span class="w"> </span><span class="s1">'dumbbell'</span><span class="p">,</span><span class="w"> </span><span class="s1">'sports'</span><span class="p">,</span><span class="mi">550</span><span class="p">);</span>
<span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="p">(</span><span class="mi">1210</span><span class="p">,</span><span class="w"> </span><span class="s1">'necklace'</span><span class="p">,</span><span class="w"> </span><span class="s1">'jewels'</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001628021390__section1132115018516"><h4 class="sectiontitle">Simple Queries</h4><p id="EN-US_TOPIC_0000001628021390__p67851133195612">Run the <strong id="EN-US_TOPIC_0000001628021390__b124356571403">SELECT... FROM...</strong> statement to obtain the result from the database.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001628021390__screen168633547133"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">category</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">newproducts</span><span class="p">;</span>
<span class="w"> </span><span class="n">category</span>
<span class="c1">------------</span>
<span class="w"> </span><span class="n">electr</span>
<span class="w"> </span><span class="n">sports</span>
<span class="w"> </span><span class="n">jewels</span>
<span class="w"> </span><span class="n">toys</span>
<span class="w"> </span><span class="n">books</span>
<span class="w"> </span><span class="n">skin</span><span class="w"> </span><span class="n">care</span>
<span class="w"> </span><span class="n">toys</span>
<span class="p">(</span><span class="mi">7</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001628021390__section151383108524"><h4 class="sectiontitle">Filtering Test Results</h4><p id="EN-US_TOPIC_0000001628021390__p988163195715">Run the <strong id="EN-US_TOPIC_0000001628021390__b151581143422">WHERE</strong> statement to filter the query result and find the queried part.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001628021390__screen475661702614"><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></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="n">newproducts</span><span class="w"> </span><span class="k">WHERE</span><span class="w"> </span><span class="n">category</span><span class="o">=</span><span class="s1">'toys'</span><span class="p">;</span>
<span class="w"> </span><span class="n">product_id</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">product_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">category</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">quantity</span>
<span class="c1">------------+--------------+----------+----------</span>
<span class="w"> </span><span class="mi">1601</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">telescope</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">toys</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">80</span>
<span class="w"> </span><span class="mi">1666</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">Frisbee</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">toys</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">244</span>
<span class="p">(</span><span class="mi">2</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001628021390__section54122345219"><h4 class="sectiontitle">Sorting Results</h4><p id="EN-US_TOPIC_0000001628021390__p578573305615">Use the <strong id="EN-US_TOPIC_0000001628021390__b27004418437">ORDER BY</strong> statement to sort query results.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001628021390__screen1723409182817"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">product_id</span><span class="p">,</span><span class="n">product_name</span><span class="p">,</span><span class="n">category</span><span class="p">,</span><span class="n">quantity</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">ORDER</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">quantity</span><span class="w"> </span><span class="k">DESC</span><span class="p">;</span>
<span class="w"> </span><span class="n">product_id</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">product_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">category</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">quantity</span>
<span class="c1">------------+--------------+-------------+----------</span>
<span class="w"> </span><span class="mi">3577</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">dumbbell</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">sports</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">550</span>
<span class="w"> </span><span class="mi">2344</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">milklotion</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">skin</span><span class="w"> </span><span class="n">care</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">320</span>
<span class="w"> </span><span class="mi">1666</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">Frisbee</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">toys</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">244</span>
<span class="w"> </span><span class="mi">1210</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">necklace</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">jewels</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">200</span>
<span class="w"> </span><span class="mi">1502</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">earphones</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">electronics</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">150</span>
<span class="w"> </span><span class="mi">1700</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">interface</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">books</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">100</span>
<span class="w"> </span><span class="mi">1601</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">telescope</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">toys</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">80</span>
<span class="p">(</span><span class="mi">7</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001628021390__section6219351165219"><h4 class="sectiontitle">Limiting the Number of Query Results</h4><p id="EN-US_TOPIC_0000001628021390__p878553375613">If you want the query to return only part of the result, you can use the <strong id="EN-US_TOPIC_0000001628021390__b147844459430">LIMIT</strong> statement to limit the number of records returned in the query result.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001628021390__screen146046274014"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">product_id</span><span class="p">,</span><span class="n">product_name</span><span class="p">,</span><span class="n">category</span><span class="p">,</span><span class="n">quantity</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">ORDER</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">quantity</span><span class="w"> </span><span class="k">DESC</span><span class="w"> </span><span class="k">limit</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span>
<span class="w"> </span><span class="n">product_id</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">product_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">category</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">quantity</span>
<span class="c1">------------+--------------+-------------+----------</span>
<span class="w"> </span><span class="mi">3577</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">dumbbell</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">sports</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">550</span>
<span class="w"> </span><span class="mi">2344</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">milklotion</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">skin</span><span class="w"> </span><span class="n">care</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">320</span>
<span class="w"> </span><span class="mi">1666</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">Frisbee</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">toys</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">244</span>
<span class="w"> </span><span class="mi">1210</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">necklace</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">jewels</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">200</span>
<span class="w"> </span><span class="mi">1502</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">earphones</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">electronics</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">150</span>
<span class="p">(</span><span class="mi">5</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001628021390__section120311115533"><h4 class="sectiontitle">Aggregated Query</h4><p id="EN-US_TOPIC_0000001628021390__p581316108312">If you want query data comprehensively, you can use the <strong id="EN-US_TOPIC_0000001628021390__b1137174154412">GROUP BY</strong> statement and aggregate functions to construct an aggregated query.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001628021390__screen461017416514"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">category</span><span class="p">,</span><span class="w"> </span><span class="n">string_agg</span><span class="p">(</span><span class="n">quantity</span><span class="p">,</span><span class="s1">','</span><span class="p">)</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">newproducts</span><span class="w"> </span><span class="k">group</span><span class="w"> </span><span class="k">by</span><span class="w"> </span><span class="n">category</span><span class="p">;</span>
<span class="w"> </span><span class="n">category</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">string_agg</span>
<span class="c1">-------------+------------</span>
<span class="w"> </span><span class="n">toys</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">80</span><span class="p">,</span><span class="mi">244</span>
<span class="w"> </span><span class="n">books</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">100</span>
<span class="w"> </span><span class="n">sports</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">550</span>
<span class="w"> </span><span class="n">jewels</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">200</span>
<span class="w"> </span><span class="n">skin</span><span class="w"> </span><span class="n">care</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">320</span>
<span class="w"> </span><span class="n">electronics</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">150</span>
</pre></div></td></tr></table></div>
</div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_1001.html">Data Read</a></div>
</div>
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