Updating a row in sql using php
There is a performance cost, naturally, but Oracle maintains that the cost of executing PL/SQL functions from SQL is continually falling.
You need to use the same number of expressions on both sides of the comparison, when using multiple operands in a comparison.
The MERGE statement (AKA "UPSERT") released in Oracle 9i is possibly one of the most useful ETL-enabling technologies built into the Oracle kernel.
This is not as serious as it sounds because you would normally have to MERGE a one-to-one or one-to-zero relationship as your join condition would be protected by the target's primary key.
As can be seen, the SQL%ROWCOUNT attribute provides us with the total MERGE count, but we have no idea of how many updates or inserts were performed, which doesn't help us when we have a production batch run to audit or debug.