SQL Stored Procedures
What is a Stored Procedure?
Prepared SQL code that you may save and reuse repeatedly is called a stored procedure.
To avoid writing the same SQL query twice, consider saving it as a stored procedure that can be called whenever needed.
A stored procedure can also receive parameters, which allow it to take action based on the parameter value or values that are supplied.
Stored Procedure Syntax
CREATE PROCEDURE procedure_name
AS
sql_statement
GO;
Execute a Stored Procedure
EXEC procedure_name;
Demo Database
Below is a selection from the “Customers” table in the Northwind sample database:
| CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
|---|---|---|---|---|---|---|
| 1 |
Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
| 2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
| 3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
| 4 |
Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
| 5 | Berglunds snabbköp | Christina Berglund | Berguvsvägen 8 | Luleå | S-958 22 | Sweden |
Stored Procedure Example
A stored procedure called “SelectAllCustomers” is created by the SQL statement that follows, and it selects every entry from the “Customers” table:
Example
CREATE PROCEDURE SelectAllCustomers
AS
SELECT * FROM Customers
GO;
Execute the stored procedure above as follows:
Example
EXEC SelectAllCustomers;
Stored Procedure With One Parameter
A stored procedure that chooses Customers from a specific City from the “Customers” table is created by the SQL statement that follows:
Example
CREATE PROCEDURE SelectAllCustomers @City nvarchar(30)
AS
SELECT * FROM Customers WHERE City = @City
GO;
Execute the stored procedure above as follows:
Example
EXEC SelectAllCustomers @City = 'London';
Stored Procedure With Multiple Parameters
It’s quite simple to set up several parameters. Simply put, as seen below, list every parameter together with the data type, separated by commas.
A stored procedure that chooses Customers from a specific City and PostalCode from the “Customers” table is created by the SQL statement that follows:
Example
CREATE PROCEDURE SelectAllCustomers @City nvarchar(30), @PostalCode nvarchar(10)
AS
SELECT * FROM Customers WHERE City = @City AND PostalCode = @PostalCode
GO;
Execute the stored procedure above as follows:
Example
EXEC SelectAllCustomers @City = 'London', @PostalCode = 'WA1 1DP';
