Stored procedure Notes By Durgesh Singh

Stored Procedure: Stored Procedure in SQL Server can be defined as the set of logical group of SQL
statements which are grouped to perform a specific task. There are many benefits of using a stored
procedure. The main benefit of using a stored procedure is that it increases the performance of the
database.The other benefits of using the Stored Procedure are given below.
Benefits of Using the Stored Procedure
1. One of the main benefits of using the Stored procedure is that it reduces the amount of information
sent to the database server. It can become a more important benefit when the bandwidth of the
network is less. Since if we send the SQL query (statement) which is executing in a loop to the server
through network and the network gets disconnected, then the execution of the SQL statement doesn't
return the expected results, if the SQL query is not used between Transaction statement and rollback
statement is not used.
2. Compilation step is required only once when the stored procedure is created. Then after it does not
require recompilation before executing unless it is modified and reutilizes the same execution plan
whereas the SQL statements need to be compiled every time whenever it is sent for execution even if
we send the same SQL statement every time.
3. It helps in re usability of the SQL code because it can be used by multiple users and by multiple
clients since we need to just call the stored procedure instead of writing the same SQL statement
every time. It helps in reducing the development time.
4. Stored procedure is helpful in enhancing the security since we can grant permission to the user for
executing the Stored procedure instead of giving permission on the tables used in the Stored
procedure.
5. Sometimes, it is useful to use the database for storing the business logic in the form of stored
procedure since it makes it secure and if any change is needed in the business logic, then we may
only need to make changes in the stored procedure and not in the files contained on the web server.
How to Write a Stored Procedure in SQL Server
Suppose there is a table called tbl_Students whose structure is given below:
CREATE TABLE tbl_Students
(
[Studentid] [int] IDENTITY(1,1) NOT NULL,
[Firstname] [nvarchar](200) NOT NULL,
[Lastname] [nvarchar](200) NULL,
[Email] [nvarchar](100) NULL
)
Support we insert the following data into the above table:
Insert into tbl_Students (Firstname, lastname, Email)
Values('Vivek', 'Johari', 'vivek@abc.com')
Values('Pankaj', 'Kumar', 'pankaj@abc.com')
Values('Amit', 'Singh', 'amit@abc.com')
Values('Manish', 'Kumar', 'manish@abc.comm')
Article by: Durgesh Kr. Singh
Software Developer(Star Group of Comp.)

Values('Abhishek', 'Singh', 'abhishek@abc.com')
Now, while writing a Stored Procedure, the first step will be to write the Create Procedure statement as
the first statement:
Create Procedure Procedure-name
(
Input parameters ,
Output Parameters (If required)
)
As
Begin
Sql statement used in the stored procedure
End
Now, suppose we need to create a Stored Procedure which will return a student name whose studentid is
given as the input parameter to the stored procedure. Then, the Stored Procedure will be:
/* Getstudentname is the name of the stored procedure*/
Create PROCEDURE Getstudentname(
@studentid INT --Input parameter , Studentid of the student
)
AS
BEGIN
SELECT Firstname+' '+Lastname FROM tbl_Students WHERE studentid=@studentid
END
We can also collect the student name in the output parameter of the Stored Procedure. For example:
/*
GetstudentnameInOutputVariable is the name of the stored procedure which
uses output variable @Studentname to collect the student name returns by the
stored procedure
*/
Create PROCEDURE GetstudentnameInOutputVariable
(
@studentid INT, --Input parameter , Studentid of the student
@studentname VARCHAR(200) OUT -- Out parameter declared with the help of OUT
keyword
)
AS
BEGIN
SELECT @studentname= Firstname+' '+Lastname FROM tbl_Students WHERE
studentid=@studentid
END
Note:-/* */ is used to write comments in one or multiple lines
-- is used to write a comment in a single line
How to Alter a Stored Procedure in a SQL Server
In SQL Server, a stored procedure can be modified with the help of the Alter keyword. Now if we want to
get student email address through the same procedure GetstudentnameInOutputVariable. So we need
to modify it by adding one more output parameter "@StudentEmail " which is shown below:

/*
Stored Procedure GetstudentnameInOutputVariable is modified to collect the
email address of the student with the help of the Alert Keyword
*/
Alter PROCEDURE GetstudentnameInOutputVariable
(
@studentid INT, --Input parameter , Studentid of the student
@studentname VARCHAR (200) OUT, -- Output parameter to collect the student name
@StudentEmail VARCHAR (200)OUT -- Output Parameter to collect the student email
)
AS
BEGIN
SELECT @studentname= Firstname+' '+Lastname,
@StudentEmail=email FROM tbl_Students WHERE studentid=@studentid
END
Note: It is not necessary that a stored procedure will have to return. There can be a case when a stored
procedure doesn't returns anything. For example, a stored procedure can be used to Insert, delete or
update a SQL statement. For example, the below stored procedure is used to insert value into the table
tbl_students.
/*
This Stored procedure is used to Insert value into the table tbl_students.
*/
Create Procedure InsertStudentrecord
(
@StudentFirstName Varchar(200),
@StudentLastName Varchar(200),
@StudentEmail Varchar(50)
)
As
Begin
Values(@StudentFirstName, @StudentLastName,@StudentEmail)
End
Execution of the Stored Procedure in SQL Server
Execution of the Stored Procedure which doesn't have an Output Parameter
A stored procedure is used in the SQL Server with the help of the "Execute" or "Exec" Keyword. For
example, if we want to execute the stored procedure "Getstudentname", then we will use the following
statement.
Execute Getstudentname 1
Exec Getstudentname 1
Execution of the Stored Procedure using the Output Parameter
If we want to execute the Stored procedure "GetstudentnameInOutputVariable" , then we first need to
declare the variable to collect the output values. For example:
Declare @Studentname as nvarchar(200) -- Declaring the variable to collect the
Studentname
Declare @Studentemail as nvarchar(50) -- Declaring the variable to collect the
Studentemail
Execute GetstudentnameInOutputVariable 1 , @Studentname output, @Studentemail output
select @Studentname,@Studentemail -- "Select" Statement is used to show the output
from Procedure ***

Stored procedure Notes By Durgesh Singh

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Stored procedure Notes By Durgesh Singh