Null statement-sequential control, PL-SQL Programming

Assignment Help:

NULL Statement

The NULL statement clearly specifies in action; it does nothing other than to pass control to the next statement. It can, though, improve the readability. In a construct allowing the substitute actions, the NULL statements serve as a placeholder. It tells the readers that the related alternative has not been overlooked, but required that no action is necessary. In the following illustration, the NULL statement shows that no action is taken for the unnamed exceptions:


EXCEPTION
WHEN ZERO_DIVIDE THEN
ROLLBACK;
WHEN VALUE_ERROR THEN
INSERT INTO errors VALUES...
COMMIT;
WHEN OTHERS THEN
NULL;
END;


Each of the clause in an IF statement should contain at least one executable statement. The
NULL statement is executable; therefore you can use it in clauses that correspond to the circumstances in which no action is taken. In the following illustration, the NULL statements emphasize that only top-rated employees get bonus:


IF rating > 90 THEN
compute_bonus(emp_id);
ELSE
NULL;
END IF;


The NULL statement is also a handy way to create stubs when designing the applications from the top down. A stub is dummy subprogram that permits you to defer the definition of a procedure or function till you test and debug the main program. In the following illustration, the NULL statement meets the requirement that at least one statement should appear in the executable part of a subprogram:




PROCEDURE debit_account (acct_id INTEGER, amount REAL) IS
BEGIN
NULL;
END debit_account;


Related Discussions:- Null statement-sequential control

Procedure, 1. Create a procedure called TAX_COST_SP to accomplish the tax c...

1. Create a procedure called TAX_COST_SP to accomplish the tax calculation task. Keep in mind that the state and subtotal values are inputs into the procedure and the procedure is

Initializing records, Initializing Records The illustration below show...

Initializing Records The illustration below shows that you can initialize a record in its type definition. Whenever you declare a record of the type TimeRec, its 3 fields supp

Obtaining a natural join by specifying the common columns, Obtaining a natu...

Obtaining a natural join by specifying the common columns Synatax: SELECT * FROM IS_CALLED JOIN IS_ENROLLED_ON USING ( StudentId ) However, a named columns join doe

Sql, If two relations R and S are joined, then the non matching tuples of b...

If two relations R and S are joined, then the non matching tuples of both R and S are ignored in __________________.

Relational operators-comparison operators, Relational Operators The rela...

Relational Operators The relational operators permit you to compare randomly complex expressions. The list below provides the meaning of each operator:

Query, ALTER TABLE bb_basketitem ADD CONSTRAINT bitems_qty_ck CHECK (quan...

ALTER TABLE bb_basketitem ADD CONSTRAINT bitems_qty_ck CHECK (quantity BEGIN INSERT INTO bb_basketitem VALUES (88,8,10.8,21,16,2,3); END; Brewbean’s wants to add a check

Cursors - syntax, Cursors   To execute the multi-row query, the Oracle...

Cursors   To execute the multi-row query, the Oracle opens an unnamed work region which stores the processing information. The cursor names the work region, access the informa

Methods in pl/sql, Methods: In normal, a method is a subprogram declar...

Methods: In normal, a method is a subprogram declared in an object type specification using the keyword MEMBER or STATIC. The method cannot have similar name as the object typ

Manipulating objects in pl sql, Manipulating Objects: You can use an o...

Manipulating Objects: You can use an object type in the CREATE TABLE statement to indicate the datatype of a column. When the table is created once, you can use the SQL statem

Package - pl/sql programming, What Is a Package? The package is a sch...

What Is a Package? The package is a schema object that group logically related PL/SQL items, types, and subprograms. The Packages usually have 2 parts, a specification & a bo

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