Chapter 3 stored procedures

Introduction To
DBMS and SQL Server
Stored Procedures

Stored Procedures
• A stored procedure is a method to encapsulate
repetitive tasks.
• A stored Procedure is actually stored in
database data dictionary

Without Stored Procedure
Employee.jsp
......................
Select * from
tbl_employee
................
Report.php
..........................
Select * from
tbl_employee
.................
.....................
Select * from
tbl_employee
viewDetails.php
..........................
.........................
Select * from
tbl_employee
...............
Database

Stored Procedure
Employee.php
..........................
..........................
exec
getName();
................
Report.php
..........................
.........................
..........................
exec
getName();
viewDetails.php
..........................
.........................
exec
getName();
...............
getName()
Begin
Select * from tbl_employee
End
Database

Advantages
• Precompiled Execution
•sqlserver compiles each stored procedure once and
then re utilizes the execution plan. This result in
tremendous performance boosts when stored
procedures are called repeatedly
• Reduced client server traffic
•If network traffic is concerned you will be happy to
learn that stored procedures can reduce long sql
queries to a single line that is transmitted between
application program and database server.

Advantages
• Efficient reuse of code and programming abstraction
•Stored procedures can be used by multiple programs
and users. If you utilize them in a planned manner,
you’ll find the development cycle takes less time.
• Enhanced Security Control
•You can grant users permission to execute stored
procedure independently of underlying table
permissions

How to create Stored Procedure ?
example
CREATE PROCEDURE getName(@id int)
as
BEGIN
Select * from tbl_user where userid=@id;
END
EXEC getName @id=1 ;

example
BEGIN
END
EXEC getName @id=1;
Is the keyword to create a new stored
procedure .we can use proc also

example
BEGIN
END
EXEC getName @id=1
Is the name of the stored
procedure that we are creating

How to create Stored Procedure
? example
CREATE PROCEDURE getName ( @id int)
BEGIN
END
Call getName @id=1;
Is the body of the stored procedure. Here we
have only a single select query statements.
We can also apply logic using the below
• DECLARE a INT; : declaring an integer
type variable
• SET a=20; : Setting value of a
to 20
• IF THEN
• ELSE IF
label1: LOOP
SET p1 = p1 + 1;
IF p1 < 10 THEN
ITERATE label1;
END IF;
LEAVE label1;
END LOOP label1;
: For conditions
: Loops

example
BEGIN
END
exec getName=@id=1;

example
BEGIN
END
exec getName @id=1;
Calling the stored procedure we’ve
just created and passing the value
1001 as its argument

example
CREATE PROCEDURE getSale1(@id int,@pri int output ,@sal int
output)
as BEGIN
Select @pri=sum(price), @sal=avg(sales) from tbl_sales
where pk_int_id=@id;
END
declare @total int
declare @sale int
exec getSale1 @id=1,@pri=@total output,@sal=@sale output;
select @total; select @sale;

• Create the below table
Create a stored procedure called
– csp_getSalary(1000) : should return the salary of employee with id as
passed in the argument
– Csp_getSalaryAtPlace(‘calicut’,@total) : should return the total salary of
employees from a perticular place
Live Task
Tbl_employee
Emp_id Emp_name Emp_age Emp_email int_salary vchr_place
1000 Deepak 24 dk@gmail.com 10000 Calicut
1001 Aneesh 23 an@gmail.com 20000 Cochin
1002 Naveen 25 nn@gmail.com 10000 Calicut
1003 Jacob 25 jb@gmail.com 30000 Cochin

Cursors
• SELECT INTO is fine for single-row queries, but many
applications require the querying of multiple rows of data.
You will use a cursor in SQL Server to accomplish this.
• A cursor lets you fetch one or more rows from a SQL result set
into stored program variables, usually with the intention of
performing some row-by-row processing on the result set.

Cursors - example
create procedure CSP_status_change
as begin
declare @done int;
set @done=0;
declare @studId int;
declare @studStatus bit;
declare @dateDif int;
declare @myCur cursor
set @myCur = cursor for select
pk_int_student_id,bln_student_status,
datediff(day,dat_fph_date,GETDATE())as date_difference from
tbl_students
join tbl_fee_payment_history on
fk_int_student_id=pk_int_student_id;
open @myCur

fetch next from @myCur into @studId,@studStatus,@dateDif;
while @@FETCH_STATUS = 0 begin
if @dateDif>15
update tbl_students set bln_student_status=0 where
pk_int_student_id=@studId;
else
update tbl_students set bln_student_status=1 where
pk_int_student_id=@studId;
fetch next from @myCur into @studId,@studStatus,@dateDif;
end;
close @myCur;
deallocate @myCur;
END;
exec CSP_status_change;
fetch next from @myCur

Questions?
“A good question deserve a good
grade…”

• Why should someone use stored procedure?
– To avoid data redundancy
– To reduce network traffic between
application server and database server
– To ensure data integrity
Self Check !!

Self Check !!
• Why should someone change the delimiter before
creating a stored procedure?
– To use ; as separation between multiple statements in a
stored procedure body
– To push the server to compile the whole body of stored
procedure all together
– Both of above
– None of above

Self Check !!
CREATE PROCEDURE simpleProc ( OUT param1 INT)
BEGIN
SELECT COUNT(*) INTO param1 FROM t ;
END
EXEC simpleProc(@a);
Select @a ;

Self Check !!
CREATE PROCEDURE simpleProc ( @param1 INT)
BEGIN
SELECT COUNT(*) INTO param1 FROM t ;
END
exec simpleProc(@a);
Select @a ;

Self Check !!
What are the uses of cursors?
•For extracting multiple rows from a table
•For extracting multiple rows into variables from a table
•For setting handlers

Chapter 3 stored procedures

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Chapter 3 stored procedures