Effects of null for table expression, PL-SQL Programming

Effects of NULL for Table Expression

Here's an important distinction between expressions denoting tables and expressions denoting multisets of rows: a table expression cannot evaluate to NULL, whereas a multiset expression can. Moreover, although a row expression can evaluate to NULL-for instance, CAST ( NULL AS ROW ( X INTEGER, Y INTEGER ) ) is a legal expression-NULL cannot appear as an element of the body of a table. Every element of the body of a table is indeed a row. However, if a table has a column whose declared type is a row type, then NULL might appear in place of a value for that column in some row of that table.

Posted Date: 1/18/2013 7:46:56 AM | Location : United States







Related Discussions:- Effects of null for table expression, Assignment Help, Ask Question on Effects of null for table expression, Get Answer, Expert's Help, Effects of null for table expression Discussions

Write discussion on Effects of null for table expression
Your posts are moderated
Related Questions
What are the rates for help in writing PL/SQL procedures and functions?

Manipulating Local Collections Within PL/SQL, to manipulate the local collection, by using theĀ  TABLE and CAST operators . The operands of CAST are a collection declared locally

Creating a SQL file 1. Open a new file in Notepad++ and save it to the location c:\mysql\bin, with the name lab8script.sql (the file extension should be .sql ). Add a MySQL co

Projection in SQL - correct version Student StudentId is enrolled on some course. SELECT DISTINCT StudentId FROM IS_ENROLLED_ON In more complicated examples it is someti

Object Type: The object type is a user-defined composite datatype which encapsulates a data structure along with the functions and procedures required to manipulate the data

Updating Objects: To change the attributes of objects in an object table, you can use the UPDATE statement, as the illustration below shows: BEGIN UPDATE persons p SET p

Project Description: I am looking to change FullCalendar to add/delete sql server data when events are removed or dropped from Calendar. Events should only be included by dra

Use of Table Expressions - Expressing Constraint Conditions With the exception of key constraints, the examples in the theory book all explicitly reference at least one relvar

Example of Shorthand for a row constraint Example: Shorthand for a row constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Mark_in_range CHECK (Mark BETWEEN 0 AND 100);

to write a heap sort program usin pl-sql