Start Updating multiple columns in oracle

Updating multiple columns in oracle

What's more, we can wrap up the whole transformation process into this one Oracle MERGE command, referencing the external table and the table function in the one command as the source for the MERGED Oracle data.

MERGE is what is known as a deterministic statement.

That is, you can only update the same row of the target table once in the same MERGE statement.

ON Clause - The ON clause specifies the condition that the MERGE operation uses to determine whether it updates or inserts.

As with any normal insert, if the insert clause is executed, all insert triggers defined on the target table are fired.

An example of a constant filter predicate would be: A predicate such as the one shown is recognized by Oracle as a special case, and Oracle makes an unconditional insert of all source rows into the table.

The benefit of this approach over just omitting the merge_update_clause, Is that Oracle still must perform a join if the merge_update_clause is left out, while with a constant filter predicate, no join is performed.

The MERGE statement is designed to combine multiple operations to reduce the complexity of mixed insert and update operations.