Parameter default values, PL-SQL Programming

Assignment Help:

Parameter Default Values

As the illustration below shows, you can initialize the IN parameters to the default values.

In that way, you can pass various numbers of actual parameters to a subprogram, accommodating or overriding the default values as you please. Furthermore, you can add new proper parameters without having to change every call to the subprogram.

PROCEDURE create_dept (

new_dname CHAR DEFAULT 'TEMP',

new_loc CHAR DEFAULT 'TEMP') IS

BEGIN

INSERT INTO dept

VALUES (deptno_seq.NEXTVAL, new_dname, new_loc);

...

END;

If an actual parameter is not passed, then the default value of its corresponding formal

parameter is used. Consider the calls below to create_dept:

create_dept;

create_dept('MARKETING');

create_dept('MARKETING', 'NEW YORK');

The first call passes no actual parameters; therefore both the default values are used. The second call passes only an actual parameter; therefore the default value for new_loc is used.

The third call passes the two actual parameters, so neither of the default value is used. Typically, you can use the positional notation to override the default values of proper parameters. Though, you cannot skip a formal parameter by leaving out its actual parameter. For illustration, the call below incorrectly relates the actual parameter 'NEW YORK' with the formal parameter new_dname:

create_dept('NEW YORK'); -- incorrect

You cannot answer the problem by leaving a placeholder for the actual parameter. For illustration below, the call is illegal:

create_dept(, 'NEW YORK'); -- illegal

In such cases, you must use named notation, which is as shown below:

create_dept(new_loc => 'NEW YORK');

You also not assign a null to an uninitialized formal parameter by leaving out its real parameter. For illustration, given the declaration

DECLARE

FUNCTION gross_pay (

emp_id IN NUMBER,

st_hours IN NUMBER DEFAULT 40,

ot_hours IN NUMBER) RETURN REAL IS

BEGIN

...

END;

The function call below does not assign a null to ot_hours:

IF gross_pay(emp_num) > max_pay THEN ... - illegal

Rather, you should pass the null explicitly, as in

IF gross_pay(emp_num, ot_hour => NULL) > max_pay THEN ...

Or you can initialize ot_hours to NULL, which is as shown:

ot_hours IN NUMBER DEFAULT NULL;

Finally, if creating a stored subprogram, you cannot use the host variables in the DEFAULT clause. The SQL Plus below illustrates causes a bad bind variable error as at the time of creation, num is merely a placeholder whose value may change:

SQL> VARIABLE num NUMBER

SQL> CREATE FUNCTION gross_pay (emp_id IN NUMBER DEFAULT :num, ...


Related Discussions:- Parameter default values

Loop statements, LOOP Statements The LOOP statements execute a series o...

LOOP Statements The LOOP statements execute a series of statements at multiple times. The loops enclose the series of statements that is to be repeated. The PL/SQL provides typ

Using exists - collection methods, Using EXISTS The EXISTS(n) returns ...

Using EXISTS The EXISTS(n) returns TRUE if the nth element in a collection exist. Or else, EXISTS(n) returns FALSE. Primarily, you use EXISTS with DELETE to maintain the spars

Number types in pl/sql, Number Types The Number types permit you to sto...

Number Types The Number types permit you to store the numeric data (real numbers, integers, and floating-point numbers), show quantities, and do computations. BINARY_INTEG

Keyword and parameter description - if statement, Keyword and Parameter Des...

Keyword and Parameter Description: boolean_expression: This is an expression which results the Boolean value TRUE, FALSE, & NULL. It is related with a series of statement

Blocks, Blocks: The fundamental program unit in the PL/SQL is the bloc...

Blocks: The fundamental program unit in the PL/SQL is the block. The PL/SQL block is defined by the keywords BEGIN, DECLARE, EXCEPTION, and END. These keywords partition the b

Keyword and parameter description - goto statement, Keyword and Parameter D...

Keyword and Parameter Description: label_name: This is an undeclared identifier which labels an executable statement or the PL/SQL block. You can use a GOTO statement to

S, Question 1. Update stock levels when the order is cancelled At times, c...

Question 1. Update stock levels when the order is cancelled At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a

Sql operators, SQL Operators The PL/SQL uses all the SQL set, compariso...

SQL Operators The PL/SQL uses all the SQL set, comparison, and row operators in the SQL statements. This part briefly describes some of these operators.  1. Comparison Opera

Declarations in sql-pl/sql, Declarations in SQL Your program stores value...

Declarations in SQL Your program stores values in the variables and constants. As the program executes, the value of the variables can change, but the values constants cannot.

Explicit cursor attributes, Explicit Cursor Attributes The cursor varia...

Explicit Cursor Attributes The cursor variable or each cursor has four attributes: %FOUND, %ISOPEN, %ROWCOUNT, and %NOTFOUND. When appended to the cursor or cursor variable, th

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd