1.

What are the modes of parameters in PL/SQL?

Answer»

The MODES of parameters in a PL/SQL subprogram includes the following:

  • IN

The IN parameter is a read-only parameter that allows you to PASS a value to the subprogram.

It acts as a constant in the subprogram. A constant, LITERAL, initialized variable, or expression can be PASSED as an IN parameter.

  • OUT

The OUT parameter acts like a variable in a subprogram. Its value can be changed unlike the IN parameter.The value can be reference after assignment.

  • IN OUT

The actual parameter is passed by value. The initial value is passed to a subprogram. The updated value is returned to the caller.

Let us see an example:

DECLARE   val number; PROCEDURE display(n IN OUT number) IS BEGIN  n := n * n; END;   BEGIN   val:= 42;   display(val);   dbms_output.put_line('Square of 42 = ' || val); END; /

The output:

Square of 42 = 1764


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