PL/SQL Loops

 PL/SQL Loops 

 Loop : 

     Like other programming language we can use loops in PLSQL programming.
    There are 3 types of loop in PLSQL.
     1) Simple Loop
     2) While Loop
     3) For Loop

 1) Simple Loop :  

Syntax:

 loop
     executable statement;
     exit when ; 
 end loop;     

    OR

 loop
     executable statement;
     if then 
         exit ; 
     end if; 
 end loop;     

  Note: 

    Exit condition is mandatory in Simple Loop otherwise program will run in infinite loop.

 Example: 

 declare
    i number:=1;
 begin
     loop
        dbms_output.put_line(i);  
        i:=i+1;
        exit when i>10;     
     end loop;
 end;     

 2) While Loop :  

  Syntax: 

 while (condition)
 loop
     executable statement;   
 end loop;     

  Note: 

    Exit condition is mandatory in Simple Loop otherwise program will run in infinite loop.

 Example: 

 declare
    i number:=1;
 begin
     while (i<=10)
     loop
        dbms_output.put_line(i);  
        i:=i+1;    
     end loop;
 end;     

 3) For Loop :  

    It is most popular loop in PLSQL as variable used for "for loop" that does not need to declare and there is no need to do manual increment.

  Syntax: 

 for i  in start_number..end_number  
 loop
     executable statement;   
 end loop;     

 Note: 

    Start_number should be less than end_number otherwise program will never print any result.

  Example: 

 begin
     for i in  1..10 
     loop
        dbms_output.put_line(i); 
     end loop;
 end;     

 4)Reverse For Loop : 

    For decrement we use "reverse" keyword.

 Syntax: 

 for i  in REVERSE  start_number..end_number  
 loop
     executable statement;   
 end loop;     

  Note:  

    Start_number should be less than end_number otherwise program will never print any result.

  Example: 

 begin
     for i in REVERSE   1..10 
     loop
        dbms_output.put_line(i); 
     end loop;
 end;