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

Create a sql database, The requirements as follows: Create a folder call...

The requirements as follows: Create a folder called "SECURITY" on the server and upload all your project files to that folder. Please note, the "SECURITY" folder is NOT to be IN

Data types in sql - interval, Data Types in SQL - Interval, Boolean I...

Data Types in SQL - Interval, Boolean INTERVAL for values denoting, not intervals (!) but durations in time, such as 5 years, 3 days, 2 minutes, and so on. BOOLEAN, con

Sql script to create and populate the tables, Create the four tables and po...

Create the four tables and populate them with the given data. Answer the following queries in SQL. 1. Get all part-color/part-city combinations. Note: Here and subsequently, the

Join query, Using a join on 3 tables, select 5 columns and 10 rows from the...

Using a join on 3 tables, select 5 columns and 10 rows from the 3 tables without the use of a Cartesian product Query: SELECT E.LAST_NAME, E.FIRST_NAME, S.BUILDING, S.BRAN

Insert command in sql, INSERT Command in SQL Loosely speaking, INSERT...

INSERT Command in SQL Loosely speaking, INSERT takes the rows of a given source table and adds them to the specified target table, retaining all the existing rows in the targ

How bulk bind helps improvement in performance?, How Bulk Binds Improve Per...

How Bulk Binds Improve Performance The assigning of values to the PL/SQL variables in SQL statements is known as binding. The binding of the whole collection at once is know

Enrolment was split - sql, Enrolment was split - SQL Example shows ho...

Enrolment was split - SQL Example shows how relvars IS_CALLED and IS_ENROLLED_ON can be derived from the original ENROLMENT relvar, using projection in the initial assignment

Cursor variables as parameters, Cursor Variables As Parameters You can...

Cursor Variables As Parameters You can declare the cursor variables as the formal parameters of the functions and procedures. In the illustration below, you define the REF CUR

%rowcount - implicit cursor attributes, %ROWCOUNT The %ROWCOUNT yields...

%ROWCOUNT The %ROWCOUNT yields the number of rows affected by the INSERT, UPDATE, or DELETE statement, or returned by a SELECT INTO statement. The %ROWCOUNT yields zero when a

Dbms, DBMS: The answer to this question is of course given in of the t...

DBMS: The answer to this question is of course given in of the theory book. This book is concerned with SQL DBMSs and SQL databases in particular. Soon we will be looking a

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