PL/SQL Merge

The PL/SQL Merge statement is a powerful tool that can be used to insert, update, or delete data in a database table.

The MERGE statement is used to merge two or more rows into one row. This is useful when you want to update or insert data into a table, and the data already exists in another table.

The syntax for the MERGE statement is as follows:

Syntax:

MERGE INTO first_table t1
USING second_table t2
ON (t1.column_id = t2.column_id)
WHEN MATCHED THEN 
UPDATE SET column1 = value1, column2 = value2 
WHEN NOT MATCHED THEN 
INSERT (column1, column2,...) 
VALUES (value1, value2, ...) ;

The PL/SQL Merge statement is a very powerful tool that can be used to make changes to a database table. When used correctly, it can save you a lot of time and effort. For example, you can use the MERGE statement to update customer information in one table with customer information from another table.

Example:

MERGE INTO customers c1
USING new_customers c2
ON (c1.customer_id = c2.customer_id)
WHEN MATCHED THEN 
UPDATE SET name = c2.name, city = c2.city 
WHEN NOT MATCHED THEN 
INSERT (name, city) 
VALUES (c2.name, c2.city) ;