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
Parameter and Keyword Description: collection_name: This keyword identifies the index-by table, nested table, or varray formerly declared within the present scope. cu

Using LOCK TABLE You use the LOCK TABLE statement to lock the whole database tables in the specified lock mode so that you can share or deny the access to them. For illustrati

COMMIT Statement The COMMIT statement explicitly makes everlasting changes to the database during the present transaction. The Changes made to the database are not considered e

THEORY OF BIOGENESIS - This theory explains that the existing living organisms originated from pre-existing living beings not from non living entities. This concept of or

Recursion versus Iteration Dissimilar the iteration, recursion is not crucial to PL/SQL programming. Any problem which can be solved using recursion can be solving using the it

Effects of NULL for union - SQL The treatment of NULL in invocations of EXCEPT is as for UNION. This is different from its treatment in those of NOT IN and quantified compari

Datatypes Every constant and variable has a datatype that specifies the storage format, constraints, and the valid range of values. The PL/SQL gives a variety of predefined dat

Manipulating Individual Elements Faraway you have manipulated an entire collection. Within the SQL, to manipulate the individual elements of the collection, and then use the ope

Expression: This is a randomly complex combination of constants, variables, literals, operators, & function calls. The simplest expression consists of a single variable. If th

Records Records are the items of the type RECORD. The Records have exclusively named fields that can store the data values of various types. And hence, a record treat associate