how to create a procedure in sql code example

Example 1: create procedure sql

CREATE PROCEDURE SelectAllCustomers @City nvarchar(30), @PostalCode nvarchar(10)
AS
SELECT * FROM Customers WHERE City = @City AND PostalCode = @PostalCode
GO;

Example 2: procedure in sql

-Stored procedure is a group of SQL
statements that has been created 
and stored in the database.
-A stored procedure will accept input 
parameters so that a single procedure
can be used over the network by several
clients using different input data.
-A stored procedures will reduce
network traffic and increase the performance. 
If we modify a stored procedure all the
clients will get the updated stored procedure.

Sample of creating a stored procedure
CREATE PROCEDURE test_display AS
SELECT FirstName, LastName FROM tb_test
EXEC test_display

Example 3: create proc

IF OBJECT_ID ( 'Production.uspGetList', 'P' ) IS NOT NULL   
    DROP PROCEDURE Production.uspGetList;  
GO  
CREATE PROCEDURE Production.uspGetList @Product varchar(40)   
    , @MaxPrice money   
    , @ComparePrice money OUTPUT  
    , @ListPrice money OUT  
AS  
    SET NOCOUNT ON;  
    SELECT p.[Name] AS Product, p.ListPrice AS 'List Price'  
    FROM Production.Product AS p  
    JOIN Production.ProductSubcategory AS s   
      ON p.ProductSubcategoryID = s.ProductSubcategoryID  
    WHERE s.[Name] LIKE @Product AND p.ListPrice < @MaxPrice;  
-- Populate the output variable @ListPprice.  
SET @ListPrice = (SELECT MAX(p.ListPrice)  
        FROM Production.Product AS p  
        JOIN  Production.ProductSubcategory AS s   
          ON p.ProductSubcategoryID = s.ProductSubcategoryID  
        WHERE s.[Name] LIKE @Product AND p.ListPrice < @MaxPrice);  
-- Populate the output variable @compareprice.  
SET @ComparePrice = @MaxPrice;  
GO