Declaring a variable v15

Generally, you must declare all variables used in a block in the declaration section of the block. A variable declaration consists of a name that's assigned to the variable and its data type. Optionally, you can initialize the variable to a default value in the variable declaration.

The general syntax of a variable declaration is:

<name> <type> [ { := | DEFAULT } { <expression> | NULL } ];

name is an identifier assigned to the variable.

type is the data type assigned to the variable.

[ := expression ], if given, specifies the initial value assigned to the variable when the block is entered. If the clause isn't given then the variable is initialized to the SQL NULL value.

The default value is evaluated every time the block is entered. So, for example, assigning SYSDATE to a variable of type DATE causes the variable to have the time of the current invocation, not the time when the procedure or function was precompiled.

This procedure shows some variable declarations that use defaults consisting of string and numeric expressions:

CREATE OR REPLACE PROCEDURE dept_salary_rpt (
    p_deptno        NUMBER
)
IS
    todays_date     DATE := SYSDATE;
    rpt_title       VARCHAR2(60) := 'Report For Department # ' || p_deptno
                             || ' on ' || todays_date;
    base_sal        INTEGER := 35525;
    base_comm_rate  NUMBER := 1.33333;
    base_annual     NUMBER := ROUND(base_sal * base_comm_rate, 2);
BEGIN
    DBMS_OUTPUT.PUT_LINE(rpt_title);
    DBMS_OUTPUT.PUT_LINE('Base Annual Salary: ' || base_annual);
END;

The following output of the procedure shows that default values in the variable declarations are assigned to the variables:

EXEC dept_salary_rpt(20);

Report For Department # 20 on 10-JUL-07 16:44:45
Base Annual Salary: 47366.55