Name resolution-naming conventions, PL-SQL Programming

Assignment Help:

Name Resolution

In potentially uncertain SQL statements, the names of the database columns take precedence over the names of the local variables and formal parameters. For e.g. the DELETE statement removes all the employees from the emp table, not just ’KING’, as Oracle suppose that both enames in the WHERE clause refer to the


database column:
DECLARE
ename VARCHAR2(10) := ’KING’;
BEGIN
DELETE FROM emp WHERE ename = ename;
In such cases, to avoid the uncertainty, prefix the names of the local variables and formal parameters with my_, as shown below:

DECLARE
my_ename VARCHAR2(10);
Or, use a block label to qualify references, as in
<

>
DECLARE
ename VARCHAR2(10) := ’KING’;
BEGIN
DELETE FROM emp WHERE ename = main.ename;

The next illustration shows that you can use a subprogram name to qualify references to a local variables and formal parameters:

FUNCTION bonus (deptno IN NUMBER, ...) RETURN REAL IS
job CHAR(10);
BEGIN
SELECT ... WHERE deptno = bonus.deptno AND job = bonus.job;


Related Discussions:- Name resolution-naming conventions

Overview of control structures-comparison operators, Overview of control st...

Overview of control structures According to the structure theorem, any computer program can be written by using the basic control structures as shown in figure below. They can b

Overloading, Overloading The PL/SQL overloads the subprogram names. T...

Overloading The PL/SQL overloads the subprogram names. That is, you can use similar name for few different subprograms as long as their formal parameters differ in the number

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

Program, heap sort program in pl/sql

heap sort program in pl/sql

Assignment statement in pl sql, Assignment Statement: The assignment s...

Assignment Statement: The assignment statement sets the present value of the variable, parameter, field, or element. The statement consists of an assignment target followed by

Difference between implicit and explicit cursor, Implicit Cursor is declare...

Implicit Cursor is declared and used by the oracle environment internally. while the explicit cursor is declared and used by the external user. more over implicitly cursors are no

%rowcount, %ROWCOUNT When its cursor or cursor variable is opened, the...

%ROWCOUNT When its cursor or cursor variable is opened, the %ROWCOUNT is zeroed. Before the first fetch, the %ROWCOUNT yields 0. Afterward, it yields the number of rows fetche

Object types and collections - performance of application, Use Object Types...

Use Object Types and Collections The Collection types and object types increase your efficiency by allowing for the realistic data modeling. The Complex real-world entities an

Update stock levels, At times, customers make mistakes in submitting their ...

At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean's wants to create a trigger that automatically updates the stock level of all pr

Initializing objects in pl sql, Initializing Objects: Till you initiali...

Initializing Objects: Till you initialize an object by calling the constructor for its object type, the object is automatically null. That is, the object itself is null, not me

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