Example of null operator - nino rule, PL-SQL Programming

Assignment Help:

Example of Null operator - NiNo Rule

If we wanted to make HIGHER_OF adhere to "NULL in, NULL out"-let's call it the NiNo rule-we would have to write something like what is shown in Example 2.1a.

Example: NiNo version of HIGHER_OF

CREATE FUNCTION HIGHER_OF ( A INTEGER, B INTEGER )

RETURNS INTEGER

CASE

WHEN A IS NULL OR B IS NULL

THEN RETURN CAST (NULL AS INTEGER);

WHEN A > B

THEN RETURN A;

ELSE RETURN B;

END CASE;

Explanation:

  • IS NULL is a monadic Boolean operator that evaluates to TRUE when its argument is "the null value", otherwise FALSE. Note, therefore, that it is our first exception to the NiNo rule, which would require it to evaluate to NULL (UNKNOWN) when its argument is "the null value".
  • CAST (NULL AS INTEGER) denotes "the null value" of type INTEGER. As in Tutorial D, the operand of RETURN must be an expression that has a declared type and NULL, on its own, does not have a declared type. The CAST operator takes an expression and a type name, separated by the "noise" word AS, and normally expresses a "type conversion"-a function that maps elements of one type to those of another that are considered to be in some defined sense equivalent. In the special case of NULL it is used to confer a type, so to speak, on something that doesn't otherwise have one.
  • AS, appearing where you might have expected just a comma, is explained by a matter of policy in SQL whereby invocations of user-defined functions, which always use commas between arguments, can be syntactically distinguished from invocations of system-defined functions.
  • OR is SQL's counterpart of the usual logical operator of that name. In A IS NULL OR B IS NULL its operands are clearly restricted to just TRUE and FALSE and that expression therefore results in TRUE if either of those operands does, otherwise FALSE.

Related Discussions:- Example of null operator - nino rule

Goto statement - sequential control, GOTO Statement The GOTO statement b...

GOTO Statement The GOTO statement branches to a label unconditionally. The label must be exclusive within its scope and should precede an executable statement or a PL/SQL block.

Types of evolution, TYPES OF EVOLUTION - Sequential evolution         ...

TYPES OF EVOLUTION - Sequential evolution                  :                    Minor changes in the gene pool of a population from one generation to the next, with the resul

Keyword and parameter description - cursors, Keyword and Parameter Descript...

Keyword and Parameter Description select_statement: This is a query which returns a result set of the rows. Its syntax is such that of select_ into_statement without the IN

Parameter modes - pl sql, Parameter Modes: You do not require to speci...

Parameter Modes: You do not require to specify a parameter mode for the input bind arguments (those used, for illustration, in the WHERE clause) as the mode defaults to IN. Th

I need sql to infopath data connection, I need SQL to infopath data connect...

I need SQL to infopath data connection Project Description: Want data retrieval connection from SQL to SharePoint infopath Skills required are Sharepoint, SQL

Magento change address format depending on store, Magento change address fo...

Magento change address format depending on store Project Description: What I need is that depending on the store in which the customer bought the address should change the fo

Inserting objects in pl sql, Inserting Objects: You can use the INSERT...

Inserting Objects: You can use the INSERT statement to add objects to an object table. In the illustration below, you insert a Person object into the object table persons:

Parameter and keyword description - packages, Parameter and Keyword Descrip...

Parameter and Keyword Description: package_name: This construct identifies the package. AUTHID Clause: This determine whether all the packaged subprograms impleme

Updating by insertion, Updating by insertion Syntax : INSERT IN...

Updating by insertion Syntax : INSERT INTO ENROLMENT VALUES (SID ('S4'), 'Devinder', CID ('C1'));

Parameter and keyword description - procedures, Parameter and Keyword Descr...

Parameter and Keyword Description: procedure_name The user-defined procedure is declared by this construct. parameter_name: This identifies the formal parameter t

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