Stored Procedures

A stored procedure is a pre-compiled SQL program that can be executed to perform a specific task. It can accept input parameters and return multiple results sets. Stored procedures are typically used to encapsulate a group of SQL statements that are executed together, to improve the performance of the database by reducing the amount of SQL that needs to be parsed and optimized, and to allow for the reuse of code.

Stored procedures are created and stored in a database and are executed using T-SQL (Transact-SQL), which is the proprietary SQL implementation used by Microsoft SQL Server. To create a stored procedure in T-SQL, you can use the CREATE PROCEDURE statement. The basic syntax for creating a stored procedure is:

CREATE PROCEDURE procedure_name
    @parameter1 datatype,
    @parameter2 datatype
AS
BEGIN
    -- SQL statements go here
END

For example, you might create a stored procedure that retrieves a list of customers from the database based on a specific country:

CREATE PROCEDURE get_customers_by_country
    @country nvarchar(50)
AS
BEGIN
    SELECT * FROM customers WHERE country = @country
END

You can execute a stored procedure by using the EXEC statement:

EXEC procedure_name @parameter1 = value1, @parameter2 = value2

For example, to execute the get_customers_by_country stored procedure and retrieve a list of customers from France, you would use the following T-SQL:

EXEC get_customers_by_country @country = 'France'