What is the purpose of MERGE in Oracle?

The MERGE statement in Oracle is used to merge data from one table into another table. It can insert data from the source table into the target table based on specified conditions, and also update data in the target table based on conditions.

The main functions of the MERGE statement are as follows:

1. Merge data: Combine the data from the source table into the target table to merge the data from the two tables.
2. Insert data: If the data from the source table doesn’t exist in the target table, it will be inserted into the target table.
3. Update data: If the data from the source table already exists in the target table, it can be updated based on specified conditions.
4. Delete data: Data can be removed from the target table if the specified conditions are met.

The MERGE statement allows for more flexible and efficient data merging compared to separately using INSERT and UPDATE statements. It can complete multiple operations in a single query, reducing the database overhead and the number of network communications.