Positioned UPDATE/DELETE

Using positioned updates/deletes with named database cursors.

The "WHERE CURRENT OF cursor-name" clause in UPDATE and DELETE statements is not supported by all database engines.

Table 1. Database server support of WHERE CURRENT OF
Database Server Type	WHERE CURRENT OF support
IBM® Informix®	Yes, see details
Microsoft™ SQL Server	Yes, see details
Oracle® MySQL / MariadDB	No, see details
Oracle Database Server	Emulated, see details
PostgreSQL	Yes, see details
SAP HANA®	No, see details
SQLite	No, see details
Dameng®	Yes, see details

Some database drivers can emulate WHERE CURRENT OF mechanisms by using rowids, but this requires additional processing. You should review the code to disable this option.

The standard SQL solution is to use primary keys in all tables and write UPDATE / DELETE statements with a WHERE clause based on the primary key:

DEFINE rec RECORD
           id    INTEGER,
           name  CHAR(100)
     END RECORD
BEGIN WORK
  UPDATE CUSTOMER SET CUSTNAME = rec.name
        WHERE CUSTID = rec.id
  ...
COMMIT WORK