Interesting properties of cross join - sql, PL-SQL Programming

Interesting properties of CROSS JOIN - SQL

Compare these with the "interesting properties of JOIN", CROSS JOIN is associative but not commutative. Unlike JOIN and NATURAL JOIN, CROSS JOIN is not idempotent. Let t be any table and let n be its cardinality. Then t CROSS JOIN t has twice as many columns as t and n2 rows. Also unlike JOIN, CROSS JOIN has no identity value. If t is a table, there is no table t0 such that t CROSS JOIN t0 = t. That's because t0 would be required to have no columns and exactly one row, but SQL doesn't recognize the existence of tables with no columns.

Posted Date: 1/18/2013 4:48:50 AM | Location : United States







Related Discussions:- Interesting properties of cross join - sql, Assignment Help, Ask Question on Interesting properties of cross join - sql, Get Answer, Expert's Help, Interesting properties of cross join - sql Discussions

Write discussion on Interesting properties of cross join - sql
Your posts are moderated
Related Questions
DBMS_OUTPUT: The Package DBMS_OUTPUT enables you to display output from the PL/SQL subprograms and blocks, that makes it easier to test and debug them. The procedure put_ line

Mixed Notation The fourth procedure call shows that you can mix the positional and named notation. In this situation, the first parameter uses the positional notation, & the s

Anatomy of a Command Figure, showing a simple SQL command, is almost identical to its counterpart in the theory book. The only difference arises from the fact that SQL uses a

Description: Demonstrate your knowledge of PL/SQL programming by writing and thoroughly testing triggers and stored procedures associated with an e-commerce application that pr

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

Implicit Rollbacks Before execute the INSERT, UPDATE, or DELETE statement, the Oracle marks an implicit savepoint . When the statement fails, the Oracle rolls back to the save

Entering and Exiting If you enter the executable part of an autonomous routine, the major transaction suspends. When you exit the routine, the major transaction resumes. To ex

Aggregate Operators SQL Supports all of the aggregate operators mentioned in the theory book and many more besides. The syntax, however, involves an unusual trick that SQL cal

Using Operator DEREF: You cannot navigate through refs within the PL/SQL procedural statements. Rather than, you should use the operator DEREF in the SQL statement. The DEREF

Example of Table Literal - SQL Example: A Table Literal (correct version) VALUES ('S1', 'C1', 'Anne'), ('S1', 'C2', 'Anne'), ('S2', 'C1', 'Boris'), ('S3', 'C3'