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

Assignment Help:

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.


Related Discussions:- Interesting properties of cross join - sql

Ensuring backward compatibility, Ensuring Backward Compatibility   The...

Ensuring Backward Compatibility   The PL/SQL Version 2 permits some abnormal behavior which Version 8 disallows. Particularly, Version 2 permits you to (i) Make the forw

Exception_init pragma - pl/sql, EXCEPTION_INIT Pragma The pragma EXCEPT...

EXCEPTION_INIT Pragma The pragma EXCEPTION_INIT relates an exception name with an Oracle error number. Which allow you to refer to any internal exception by the name and to wri

Translate the given er schema into sql, Consider the schema for FreeCheckin...

Consider the schema for FreeChecking Bank, that we designed given below. Translate the given ER schema into SQL CREATE TABLE statements (indicating primary key, unique and foreign

Using aliases-declarations in sql, Using Aliases The Select-list items f...

Using Aliases The Select-list items fetched from a cursor related with the %ROWTYPE should have simple names or, if they are expressions, should have aliases. In the example bel

Oracle development , Write a stored procedure that accepts the post code in...

Write a stored procedure that accepts the post code in which the customer resides as the input parameter. The procedure should then use an explicit cursor to display comprehensive

Multiple assignment - sql, Multiple Assignment- SQL SQL supports mult...

Multiple Assignment- SQL SQL supports multiple assignment to local variables and also applies multiple assignment semantics in SET clauses of UPDATE statements, but does not

Declaring subprograms, Declaring Subprograms   You can declare subprog...

Declaring Subprograms   You can declare subprograms in any PL/SQL subprogram, block, or package. But, you should declare subprograms at the end of the declarative part after a

Out mode - parameter modes, OUT Mode An OUT parameter returns values t...

OUT Mode An OUT parameter returns values to the caller of a subprogram. Within the subprogram, an OUT parameter act like a variable. That means that you can use an OUT formal

Indeterminacy in sql, Indeterminacy in SQL Some SQL expressions are ac...

Indeterminacy in SQL Some SQL expressions are actually not function invocations at all in the mathematical sense, being indeterminate-invocations operating on identical input

Keyword & parameter description - exceptions, Keyword & Parameter Descripti...

Keyword & Parameter Description: WHEN: This keyword introduces the exception handler. You can have many exceptions execute the similar sequence of the statements by follo

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