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99 lines
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HTML
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<title>Sort sequences and normalization in SQL</title>
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</head>
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<body id="rbafyussisql"><a name="rbafyussisql"><!-- --></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">Sort sequences and normalization in SQL</h1>
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<div><p>A sort sequence defines how characters in a character set relate
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to each other when they are compared or ordered. Normalization allows you
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to compare strings that contain combining characters.</p>
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<p> The sort sequence is used for all character, and UCS-2 and UTF-16 graphic
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comparisons performed in SQL statements. There are sort sequence tables for
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both single byte and double byte character data. Each single byte sort sequence
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table has an associated double byte sort sequence table, and vice versa. Conversion
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between the two tables is performed when necessary to implement a query. In
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addition, the CREATE INDEX statement has the sort sequence (in effect at the
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time the statement was run) applied to the character columns referred to in
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the index.</p>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rbafyssorder.htm">Sort sequence used with ORDER BY and row selection</a></strong><br />
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To see how to use a sort sequence, run the examples against the STAFF table shown in this topic.</li>
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<li class="ulchildlink"><strong><a href="rbafyssviews.htm">Sort sequence and views</a></strong><br />
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Views are created with the sort sequence that was in effect when the CREATE VIEW statement was run.</li>
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<li class="ulchildlink"><strong><a href="rbafyssindex.htm">Sort sequence and the CREATE INDEX statement</a></strong><br />
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Indexes are created using the sort sequence that was in effect when the CREATE INDEX statement was run.</li>
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<li class="ulchildlink"><strong><a href="rbafyssconstraints.htm">Sort sequence and constraints</a></strong><br />
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Unique constraints are implemented with indexes. If the table on which a unique constraint is added was defined with a sort sequence, the index will be created with that same sort sequence.</li>
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<li class="ulchildlink"><strong><a href="rbafyicu.htm">ICU sort sequence</a></strong><br />
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<span>When an ICU (International Components
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for Unicode) sort sequence table is used, the database uses the system's ICU
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support (Option 39) to determine the weight of the data according to language-specific
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rules specified by to the locale of the table.</span></li>
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<li class="ulchildlink"><strong><a href="rbafynormal.htm">Normalization</a></strong><br />
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Normalization allows you to compare strings that contain combining characters.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafykickoff.htm" title="These topics describe the iSeries server implementation of the Structured Query Language (SQL) using DB2 UDB for iSeries and the DB2 UDB Query Manager and SQL Development Kit Version 5 licensed program.">SQL programming</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rbafyviewnt.htm" title="A view can be used to access data in one or more tables or views. You create a view by using a SELECT statement.">Create and use views</a></div>
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<div><a href="rbafycrtindx.htm" title="You can use indexes to sort and select data. In addition, indexes help the system retrieve data faster for better query performance.">Add indexes</a></div>
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<div><a href="rbafywhere.htm" title="The WHERE clause specifies a search condition that identifies the row or rows you want to retrieve, update, or delete.">Specify a search condition using the WHERE clause</a></div>
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<div><a href="rbafygroup.htm" title="The GROUP BY clause allows you to find the characteristics of groups of rows rather than individual rows.">GROUP BY clause</a></div>
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<div><a href="rbafyhaving.htm" title="The HAVING clause specifies a search condition for the groups selected by GROUP BY clause.">HAVING clause</a></div>
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<div><a href="rbafyorderby.htm" title="The ORDER BY clause specifies the particular order in which you want selected rows returned. The order is sorted by ascending or descending collating sequence of a column's or expression's value.">ORDER BY clause</a></div>
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<div><a href="rbafydupl.htm" title="When SQL evaluates a select-statement, several rows might qualify to be in the result table, depending on the number of rows that satisfy the select-statement's search condition. Some of the rows in the result table might be duplicates.">Handle duplicate rows</a></div>
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<div><a href="rbafycomsrch.htm" title="In addition to the basic comparison predicates (=, >, <, and so on), a search condition can contain any of the predicates BETWEEN, IN, EXISTS, IS NULL, and LIKE.">Define complex search conditions</a></div>
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<div><a href="rbafykeyu.htm" title="Using the UNION keyword, you can combine two or more subselects to form a fullselect.">Use UNION keyword to combine subselects</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../db2/rbafzmstsortsequence.htm">Sort Sequence</a></div>
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</div>
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</div>
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</body>
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