FOR LOOP is the most used loop structure in Oracle. FOR LOOP executes specified number of times which defined in the definition. So generally no need of any specific exit command for FOR LOOPs. FOR LOOP is suitable when the number of iterations are known.
Examples:-
1) Printing 1 to 10 in ascending order
SQL> set serveroutput on
SQL> begin
2 for i in 1..10 loop
3 dbms_output.put_line(‘value of i = ‘ || i);
4 end loop;
5 end;
6 /
value of i = 1
value of i = 2
value of i = 3
value of i = 4
value of i = 5
value of i = 6
value of i = 7
value of i = 8
value of i = 9
value of i = 10
PL/SQL procedure successfully completed.
2) Printing 1 to 10 in descending order – Using reverse keyword
SQL> begin
2 for i in reverse 1..10 loop
3 dbms_output.put_line(‘value of i = ‘ || i);
4 end loop;
5 end;
6 /
value of i = 10
value of i = 9
value of i = 8
value of i = 7
value of i = 6
value of i = 5
value of i = 4
value of i = 3
value of i = 2
value of i = 1
PL/SQL procedure successfully completed.
Note :- In the above example variable ‘i’ is called index. Index variable cannot be modified programmatically ( or cannot be used as assignment target). see below
SQL> begin
2 for i in 1..10 loop
3 dbms_output.put_line(‘value of i = ‘ || i);
4 i := 5;
5 end loop;
6 end;
7 /
i := 5;
*
ERROR at line 4:
ORA-06550: line 4, column 3:
PLS-00363: expression ‘I’ cannot be used as an assignment target
ORA-06550: line 4, column 3:
PL/SQL: Statement ignored
Read also – While loop , goto statement
