Wednesday, September 28, 2011

PL/SQL: Handling Variables


Shafeen


  • Variables must be declared first before the usage. The PL/SQL variables can be a scalar type such as DATE, NUMBER, VARCHAR(2), DATE, BOOLEAN, LONG and CHAR, or a composite type, such  array type VARRAY.
  • Only TRUE and FALSE can be assigned to BOOLEAN type of variables.
  • AND, OR, NOT operators can be used to connect BOOLEAN values.
  • % TYPE attribute can be used to define a variable which is of type the same as a database column's type definition.
  • Users can customize the variable types by using TYPE ... IS ... statement.
The following code block illustrates the use of TYPE..IS... and VARRAY. In this sample, a type v_arr is defined as an variable array of maximum 25 elements which are of type NUMBER(3).  Then a variable v1 is defined as type v_arr .    This sample code also demonstrates the use of %TYPE attribute.
DECLARE
TYPE v_arr IS VARRAY(25) of NUMBER(3);

v1 v_arr;
v_empno employee.empno%TYPE;

BEGIN

    v1(2) := 3;
    DBMS_OUTPUT.PUT_LINE('The Value of v1(2) = ' || v1(2)); 

      v_empno  := 4;
END;
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