Control Flow in PL/SQL

PL/SQL allows you to branch and create loops in a fairly familiar way. An IF statement looks like: 
   IF <condition>  THEN <statement_list>
   ELSE <statement_list>
   END IF;
The ELSE part is optional. If you want a multiway branch, use: 
   IF <condition_1> THEN ...
   ELSIF <condition_2> THEN ...
   ... ...
   ELSIF <condition_n> THEN ...
   ELSE ...
   END IF;
The following is an example, slightly modified from the previous one, where now we only do the insertion if the second component is 1. If not, we first add 10 to each component and then insert: 

SQL> DECLARE 
  2    a  NUMBER; 
  3    b  NUMBER; 
  4  BEGIN 
  5    SELECT  e, f  INTO  a, b  FROM  T1  WHERE  e > 1; 
  6    IF  b = 1  THEN 
  7      INSERT INTO  T1  VALUES( b, a ); 
  8    ELSE 
  9      INSERT INTO  T1  VALUES( b+10, a+10 ); 
 10    END IF; 
 11  END; 
 12  / 
PL/SQL procedure successfully completed.

Loops are created with the following: 
   LOOP
     <loop_body>   /* a list of statements */
   END LOOP;



      We get used to that, we endure, we harden,    
      we batten down the hatches (prepare for the trouble)    
      to protect our habits.