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Download Informix Guide to SQL: Syntax
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ALTER FRAGMENT Element frag-expression Purpose The modified range, hash, or arbitrary expression mod-dbspace The modified dbspace new-dbspace The dbspace that contains the modified information Restrictions The fragment expression can contain only columns from the current table and only data values from a single row. No subqueries, stored procedures, current date/time functions, or aggregates are allowed in frag-expression. The dbspace must exist when you execute the statement. The dbspace must exist when you execute the statement. Syntax Condition, p. 1-643, and Expression, p. 1-671 Identifier, p. 1-723 Identifier, p. 1-723 General Usage When you use the MODIFY clause, the underlying dbspaces are not affected. Only the fragment data within the dbspaces is affected. You cannot change a REMAINDER fragment into a nonremainder fragment if records within the REMAINDER fragment do not pass the new expression. Warning: When you specify a date value in a fragment expression in the MODIFY clause, make sure to specify 4 digits instead of 2 digits for the year. When you specify a 4-digit year, the DBCENTURY environment variable has no effect on the distribution scheme. When you specify a 2-digit year, the DBCENTURY environment variable can affect the distribution scheme and can produce unpredictable results. See the “Informix Guide to SQL: Reference” for more information on the DBCENTURY environment variable. Changing the Expression in an Existing Dbspace When you use the MODIFY clause to change an expression without changing the dbspace storage for the expression, you must use the same name for the mod dbspace and the new dbspace. The following example shows how to use the MODIFY clause to change an existing expression: ALTER FRAGMENT ON TABLE cust_acct MODIFY dbsp1 to acct_num < 65 IN dbsp1 SQL Statements 1-41
