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<h1 class="topictitle1">Use EXCEPT keyword</h1>
<div><p>The EXCEPT keyword returns the result set of the first subselect
minus any matching rows from the second subselect.</p>
<div class="section"><p>Suppose you want to find a list of employee numbers that includes:</p>
<ul><li>People in department D11</li>
<li><em>Minus</em> those people whose assignments include projects MA2112, MA2113,
and AD3111</li>
</ul>
<p>This query returns all of the people in department D11 who are <em>not</em> working
on projects MA2112, MA2113, and AD3111.</p>
</div>
<div class="section"><p>To do this, specify: </p>
<pre><strong>SELECT</strong> EMPNO
<strong>FROM</strong> CORPDATA.EMPLOYEE
<strong>WHERE</strong> WORKDEPT = 'D11'
<strong>EXCEPT</strong>
<strong>SELECT</strong> EMPNO
<strong>FROM</strong> CORPDATA.EMPPROJACT
<strong>WHERE</strong> PROJNO = 'MA2112' <strong>OR</strong>
PROJNO = 'MA2113' <strong>OR</strong>
PROJNO = 'AD3111'
<strong>ORDER BY</strong> EMPNO</pre>
</div>
<div class="section"><p>To better understand the results from these SQL statements, imagine
that SQL goes through the following process:</p>
</div>
<div class="section"><p>Step 1. SQL processes the first SELECT statement:</p>
<pre><strong>SELECT</strong> EMPNO
<strong>FROM</strong> CORPDATA.EMPLOYEE
<strong>WHERE</strong> WORKDEPT = 'D11'</pre>
<p>Which results in an interim
result table:</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="hsides" border="1" rules="all"><thead align="left"><tr valign="top"><th valign="top" id="d0e89">EMPNO from CORPDATA.EMPLOYEE</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e89 ">000060</td>
</tr>
<tr><td valign="top" headers="d0e89 ">000150</td>
</tr>
<tr><td valign="top" headers="d0e89 ">000160</td>
</tr>
<tr><td valign="top" headers="d0e89 ">000170</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">000180</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">000190</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">000200</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">000210</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">000220</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">200170</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e89 ">200220</td>
</tr>
</tbody>
</table>
</div>
<p>Step 2. SQL processes the second SELECT statement:</p>
<pre><strong>SELECT</strong> EMPNO
<strong>FROM</strong> CORPDATA.EMPPROJACT
<strong>WHERE</strong> PROJNO='MA2112' <strong>OR</strong>
PROJNO= 'MA2113' <strong>OR</strong>
PROJNO= 'AD3111'</pre>
<p>Which results in another interim
result table:</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="hsides" border="1" rules="all"><thead align="left"><tr valign="top"><th valign="top" id="d0e150">EMPNO from CORPDATA.EMPPROJACT</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e150 ">000230</td>
</tr>
<tr><td valign="top" headers="d0e150 ">000230</td>
</tr>
<tr><td valign="top" headers="d0e150 ">000240</td>
</tr>
<tr><td valign="top" headers="d0e150 ">000230</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000230</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000240</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000230</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000150</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000170</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000190</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000170</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000190</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000150</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000160</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000180</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000170</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000210</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e150 ">000210</td>
</tr>
</tbody>
</table>
</div>
<p>Step 3. SQL takes the first interim result table, removes all of
the rows that also appear in the second interim result table, removes duplicate
rows, and orders the result:</p>
<pre><strong>SELECT</strong> EMPNO
<strong>FROM</strong> CORPDATA.EMPLOYEE
<strong>WHERE</strong> WORKDEPT = 'D11'
<strong>EXCEPT</strong>
<strong>SELECT</strong> EMPNO
<strong>FROM</strong> CORPDATA.EMPPROJACT
<strong>WHERE</strong> PROJNO='MA2112' <strong>OR</strong>
PROJNO= 'MA2113' <strong>OR</strong>
PROJNO= 'AD3111'
<strong>ORDER BY</strong> EMPNO</pre>
<p>Which results in a combined result table
with values in ascending sequence:</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="hsides" border="1" rules="all"><thead align="left"><tr valign="top"><th valign="top" id="d0e247">EMPNO</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e247 ">000060</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e247 ">000200</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e247 ">000220</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e247 ">200170</td>
</tr>
<tr valign="top"><td valign="top" headers="d0e247 ">200220</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafytexas.htm" title="Learn a variety of ways of tailoring your query to gather data using the SELECT statement. One way to do this is to use the SELECT statement in a program to retrieve a specific row (for example, the row for an employee). Furthermore, you can use clauses to gather data in a specific way.">Retrieve data using the SELECT statement</a></div>
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