Cursor behavior
If a database is not ANSI-compliant, you must use the FOR UPDATE
keywords when you declare an update cursor for a SELECT statement.
The SELECT statement must also meet the following conditions:
- It selects from a single table.
- It does not include any aggregate functions.
- It does not include the DISTINCT, GROUP BY, INTO TEMP, ORDER BY, UNION, or UNIQUE clauses and keywords.
In ANSI-compliant databases, the FOR UPDATE keywords are implicit when you declare a cursor, and all cursors that meet the restrictions that the preceding list describes are potentially update cursors. You can specify that a cursor is read-only with the FOR READ ONLY keywords on the DECLARE statement.
For more information, see the description of the DECLARE statement in the IBM® Informix® Guide to SQL: Syntax.