PL/SQL - Basic Loop Statement

PL/SQL - Basic Loop Statement

Basic loop structure encloses sequence of statements in between the LOOP and END LOOP statements. With each iteration, the sequence of statements is executed and then control resumes at the top of the loop.
Syntax
The syntax of a basic loop in PL/SQL programming language is −

LOOP 
   Sequence of statements; 
END LOOP; 

Here, the sequence of statement(s) may be a single statement or a block of statements. An EXIT statement or an EXIT WHEN statement is required to break the loop.
Example

Dispaly 1-10 Numbers Numbers

DECLARE 
   x number := 1; 
BEGIN 
   LOOP 
      dbms_output.put_line(x); 
      x := x + 1; 
      IF x > 10 THEN 
         exit; 
      END IF; 
   END LOOP; 
   -- after exit, control resumes here  
   dbms_output.put_line('After Exit x is: ' || x); 
END; 
/

When the above code is executed at the SQL prompt, it produces the following result −
1
2
3
4
5
6
7
8
9
10
After Exit x is: 11

PL/SQL procedure successfully completed.

You can use the EXIT WHEN statement instead of the EXIT statement −

DECLARE 
   x number := 1; 
BEGIN 
   LOOP 
      dbms_output.put_line(x); 
      x := x + 1; 
      exit WHEN x > 10; 
   END LOOP; 
   -- after exit, control resumes here 
   dbms_output.put_line('After Exit x is: ' || x); 
END; 
/

When the above code is executed at the SQL prompt, it produces the following result −
1
2
3
4
5
6
7
8
9
10
After Exit x is: 11

PL/SQL procedure successfully completed.

Dispaly 10-1 Numbers Numbers

    
declare 
x int:=10;
begin
loop

dbms_output.put_line(x);
if(x<=0) then
exit;
end if;
x:=x-1;

end loop;
end;
/

Dispaly Even Numbers Numbers

declare 
x int:=10;
begin
loop

if(x mod 2=0)then
dbms_output.put_line(x);
end if;

if(x<=0) then
exit;
end if;
x:=x-1;

end loop;
end;
/

Nested Basic Loop

One basic loop with in another basic loop
Syntax

loop
	loop
	...
	...
	end loop;
...
...
end loop;

in the above syntax
outerloop row
innerloop column

Example #1

***
***
***
***
***
***

declare 
r int;
c int;

begin
r:=1;
loop
	c:=1;
	loop
	dbms_output.put('*');
	if(c>=3) then 
	exit;
	end if;
	c:=c+1;
	

	end loop;

dbms_output.put_line('');
if(r>5) then
exit;
end if;
r:=r+1;
end loop;
end;
/

Example #2

*
**
***
****
*****
******

declare 
r int;
c int;

begin
r:=1;
loop
	c:=1;
	loop
	dbms_output.put('*');
	if(c>=r) then 
	exit;
	end if;
	c:=c+1;
	end loop;

dbms_output.put_line('');
if(r>5) then
exit;
end if;
r:=r+1;
end loop;
end;
/

Example #3

******
*****
****
***
**
*

declare 
r int;
c int;

begin
r:=1;
loop
	c:=6;
	loop
	dbms_output.put('*');
	if(c<=r) then 
	exit;
	end if;
	c:=c-1;
	end loop;

dbms_output.put_line('');
if(r>5) then
exit;
end if;
r:=r+1;
end loop;
end;
/

Example #4

*******
*     *
*     *
*     *
*     *
*     *
*******


declare 
r int;
c int;

begin
r:=1;
loop
	c:=7;
	loop
	if(r=1 or r=7 or c=1 or c=7) then
	dbms_output.put('*');
	else
	dbms_output.put(' ');
	end if;
	if(c<=1) then 
	exit;
	end if;
	c:=c-1;
	end loop;

dbms_output.put_line('');
if(r>=7) then
exit;
end if;
r:=r+1;
end loop;
end;
/

Example #5

   *   
   *   
   *   
*******
   *   
   *   
   *   


declare 
r int;
c int;

begin
r:=1;
loop
	c:=7;
	loop
	if(r=4 or c=4) then
	dbms_output.put('*');
	else
	dbms_output.put(' ');
	end if;
	if(c<=1) then 
	exit;
	end if;
	c:=c-1;
	end loop;

dbms_output.put_line('');
if(r>=7) then
exit;
end if;
r:=r+1;
end loop;
end;
/

Example #6

      *
     **
    ***
   ****
  *****
 ******
*******



declare 
r int;
c int;

begin
r:=1;
loop
	c:=7;
	loop
	if(r>=c) then
	dbms_output.put('*');
	else
	dbms_output.put(' ');
	end if;
	if(c<=1) then 
	exit;
	end if;
	c:=c-1;
	end loop;

dbms_output.put_line('');
if(r>=7) then
exit;
end if;
r:=r+1;
end loop;
end;
/