Can we DELETE using MERGE in Oracle?
2 Answers. No, you cannot delete rows that have not been updated by the merge command. Specify the DELETE where_clause to clean up data in a table while populating or updating it.
What is MERGE into in Oracle?
The Oracle MERGE statement selects data from one or more source tables and updates or inserts it into a target table. The MERGE statement allows you to specify a condition to determine whether to update data from or insert data into the target table.
Does MERGE auto commit Oracle?
Since MERGE is a single statement, both the UPDATE and the INSERT operate under the same transaction. If either of the operation fails, both the operations are rolled back when AUTOCOMMIT is ON. If the MERGE statement fails within a user transaction, the entire transaction is aborted.
Is MERGE faster than UPDATE in Oracle?
The UPDATE statement will most likely be more efficient than a MERGE if the all you are doing is updating rows. Given the complex nature of the MERGE command’s match condition, it can result in more overhead to process the source and target rows.
When to use update delete or merge in SQL?
So, no big deal to write a sql statement that handles changes in the source table and moves them to a target table. Even removing rows from target, when they are logically deleted in the source should not be a problem as there is an update delete clause in the merge command.
What does delete where do in merge do?
Specify the DELETE where_clause to clean up data in a table while populating or updating it. The only rows affected by this clause are those rows in the destination table that are updated by the merge operation. The DELETE WHERE condition evaluates the updated value, not the original value that was evaluated by the UPDATE SET
When do you use MERGE statement in Oracle?
USING Use the MERGE statement to select rows from one or more sources for update or insertion into a table or view. You can specify conditions to determine whether to update or insert into the target table or view. This statement is a convenient way to combine multiple operations.
When to use the MERGE statement in DML?
Use the MERGE statement to select rows from one or more sources for update or insertion into a table or view. You can specify conditions to determine whether to update or insert into the target table or view. This statement is a convenient way to combine multiple operations. It lets you avoid multiple INSERT, UPDATE, and DELETE DML statements.