Positioned updates of columns
Certain SQL processing options affect the use of the FOR UPDATE clause to achieve positioned column updates.
The NOFOR SQL processing option affects the use of the FOR UPDATE clause. The NOFOR option is in effect when either of the following are true:
- The NOFOR option is specified.
- The STDSQL(YES) option is in effect.
Otherwise, the NOFOR option is not in effect. The following table summarizes the differences when the option is in effect and when the option is not in effect:
| When NOFOR is in effect | When NOFOR is not in effect |
|---|---|
| The use of the FOR UPDATE clause in the SELECT statement of the DECLARE CURSOR statement is optional. This clause restricts updates to the specified columns and causes the acquisition of update locks when the cursor is used to fetch a row. If no columns are specified, positioned updates can be made to any updatable columns in the table or view that is identified in the first FROM clause in the SELECT statement. If the FOR UPDATE clause is not specified, positioned updates can be made to any columns that the program has DB2® authority to update. | The FOR UPDATE clause must be specified. |
| DBRMs must be built entirely in virtual storage, which might possibly increase the virtual storage requirements of the DB2 precompiler or coprocessor. However, creating DBRMs entirely in virtual storage might cause concurrency problems with DBRM libraries. | DBRMs can be built incrementally using the DB2 precompiler or coprocessor. |
SQL processing options do not affect ODBC behavior.