Modifying and Deleting Stored Procedures

Introduction

In SQL, Stored Procedures are pre-compiled objects that are stored on the database data-tier. They can accept input parameters and return multiple values of output parameters; in addition, they can contain programming statements and complex logic. In this article, we will be discussing how to modify and delete stored procedures in SQL.

Modifying Stored Procedures

There are two ways to modify a stored procedure in SQL:

1. Using ALTER PROCEDURE

The ALTER PROCEDURE statement is used to modify an existing stored procedure. The basic syntax is as follows:

ALTER PROCEDURE procedure_name 
@parameter data_type, 
AS 
BEGIN 
   -- SQL commands
END;

To modify a stored procedure using ALTER PROCEDURE, you need to provide the full definition of the stored procedure. The changes you make will replace the existing definition of the stored procedure.

Example:

ALTER PROCEDURE SelectAllCustomers
AS
BEGIN
   SELECT * FROM Customers
END;

In this example, the SelectAllCustomers stored procedure is altered to select all records from the Customers table.

2. Using DROP and CREATE

Another way to modify a stored procedure is to delete it and recreate it.

First, you use the DROP PROCEDURE statement to delete the stored procedure:

DROP PROCEDURE procedure_name;

Then, you use the CREATE PROCEDURE statement to create the stored procedure with the new definition:

CREATE PROCEDURE procedure_name
AS
BEGIN
   -- SQL commands
END;

Example:

DROP PROCEDURE SelectAllCustomers;

CREATE PROCEDURE SelectAllCustomers
AS
BEGIN
   SELECT * FROM Customers WHERE Country = 'USA'
END;

In this example, the SelectAllCustomers stored procedure is first dropped, then recreated so that it now selects only the customers from the USA.

Deleting Stored Procedures

Deleting a stored procedure is straightforward. You use the DROP PROCEDURE statement, followed by the name of the procedure you want to delete.

DROP PROCEDURE procedure_name;

Example:

DROP PROCEDURE SelectAllCustomers;

In this example, the SelectAllCustomers stored procedure is deleted.

Conclusion

Modifying and deleting stored procedures in SQL is a straightforward process. Whether you want to change the logic of your stored procedure or remove it altogether, you can do so using the ALTER PROCEDURE, DROP PROCEDURE, and CREATE PROCEDURE statements.