129 lines
7.0 KiB
HTML
129 lines
7.0 KiB
HTML
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="abstract" content="The format and syntax shown here are very basic. SELECT statements can be more varied than the examples presented in this topic." />
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<meta name="description" content="The format and syntax shown here are very basic. SELECT statements can be more varied than the examples presented in this topic." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>Basic SELECT statement</title>
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</head>
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<body id="rbafyselectbasic"><a name="rbafyselectbasic"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Basic SELECT statement</h1>
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<div><p>The format and syntax shown here are very basic. SELECT statements
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can be more varied than the examples presented in this topic.</p>
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<div class="section"><p>You can write SQL statements on one line or on many lines. For
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SQL statements in precompiled programs, the rules for the continuation of
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lines are the same as those of the host language (the language the program
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is written in). A SELECT statement can also be used by a cursor in a program.
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Finally, a SELECT statement can be prepared in a dynamic application. </p>
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<div class="note"><span class="notetitle">Notes:</span> <ol><li>The SQL statements described in this section can be run on SQL tables
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and views, and database physical and logical files.</li>
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<li>Character strings specified in an SQL statement (such as those used with
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WHERE or VALUES clauses) are case sensitive; that is, uppercase characters
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must be entered in uppercase and lowercase characters must be entered in lowercase.
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<pre><strong>WHERE</strong> ADMRDEPT='a00' (does not return a result)
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<strong>WHERE</strong> ADMRDEPT='A00' (returns a valid department number)</pre>
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<p>Comparisons
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may not be case sensitive if a shared-weight sort sequence is being used where
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uppercase and lowercase characters are treated as the same character.</p>
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</li>
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</ol>
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</div>
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</div>
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<div class="section"><p>A SELECT statement can include the following:</p>
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</div>
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<div class="section"> <ol><li>The name of each column you want to include in the result.</li>
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<li>The name of the table or view that contains the data.</li>
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<li>A search condition to identify the rows that contain the information you
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want.</li>
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<li>The name of each column used to group your data.</li>
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<li>A search condition that uniquely identifies a group that contains the
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information you want.</li>
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<li>The order of the results so a specific row among duplicates can be returned.</li>
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</ol>
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</div>
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<div class="section"><p>A SELECT statement looks like this:</p>
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<pre> <strong>SELECT</strong> column names
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<strong>FROM</strong> table or view name
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<strong>WHERE</strong> search condition
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<strong>GROUP BY</strong> column names
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<strong>HAVING</strong> search condition
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<strong>ORDER BY</strong> column-name</pre>
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</div>
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<div class="section"><p>The SELECT and FROM clauses must be specified. The other clauses
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are optional.</p>
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</div>
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<div class="section"><p>With the SELECT clause, you specify the name of each column you
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want to retrieve. For example: </p>
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<pre> <strong>SELECT</strong> EMPNO, LASTNAME, WORKDEPT
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</pre>
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</div>
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<div class="section"><p>You can specify that only one column be retrieved, or as many
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as 8000 columns. The value of each column you name is retrieved in the order
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specified in the SELECT clause.</p>
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</div>
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<div class="section"><p>If you want to retrieve all columns (in the same order as they
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appear in the table's definition), use an asterisk (*) instead of naming the
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columns: </p>
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<pre> <strong>SELECT</strong> *
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</pre>
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</div>
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<div class="section"><p>The FROM clause specifies the table that you want to select data <em>from</em>.
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You can select columns from more than one table. When issuing a SELECT, you
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must specify a FROM clause. Issue the following statement: </p>
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<pre><strong>SELECT</strong> *
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<strong>FROM</strong> EMPLOYEE</pre>
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<p>The result is all of the columns
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and rows from table EMPLOYEE.</p>
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</div>
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<div class="section"><p>The SELECT list can also contain expressions, including constants,
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special registers, and scalar fullselects. An AS clause can be
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used to give the resulting column a name. For example, issue the following
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statement: </p>
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<pre><strong>SELECT</strong> LASTNAME, SALARY * .05 <strong>AS</strong> RAISE
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<strong>FROM</strong> EMPLOYEE
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<strong>WHERE</strong> EMPNO = '200140'</pre>
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<p>The result of this statement
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is:</p>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="hsides" border="1" rules="all"><caption>Table 1. Results for query</caption><thead align="left"><tr><th valign="top" id="d0e176">LASTNAME</th>
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<th valign="top" id="d0e178">RAISE</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" headers="d0e176 ">NATZ</td>
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<td valign="top" headers="d0e178 ">1421</td>
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</tr>
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</tbody>
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</table>
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</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="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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</div>
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</div>
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</body>
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</html>
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