SQL - What is Cartesian product in the SQL?

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What is Cartesian product in the SQL?

Total Answers and Comments: 5

Last Update: February 26, 2008 Asked by: Sameer Yajurvedi

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when a join condition is omited when getting result from two tables then that kind of query gives us Cartesian product, in which all combination of rows displayed. All rows in the first table is joined to all rows of second table......

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hereoracleuser

January 09, 2007 16:23:15

RE: What is Cartesian product in the SQL?

when a join condition is omited when getting result from two tables then that kind of query gives us Cartesian product in which all combination of rows displayed. All rows in the first table is joined to all rows of second table......

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January 29, 2007 07:34:08

Ajay Nerumati

Member Since: January 2007 Contribution: 3

RE: What is Cartesian product in the SQL?

Hi All It is a common requirement in Oracle to join tables using join syntax you end up getting a cartesian product 1. when a join condition is ommited .2. The condition is not a valid condition.Under such curcumstances all rows of table 'A' are mapped to table 'N' resulting in A*N number or rows.Thank you Ajay Nerumati.Oracle DBA

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February 12, 2008 16:09:23

g_sidhu

Member Since: August 2007 Contribution: 122

RE: What is Cartesian product in the SQL?

Cartesian Products: If two tables in a join query have no join condition Oracle returns their Cartesian product. Oracle combines each row of one table with each row of the other. A Cartesian product always generates many rows and is rarely useful.• A Cartesian product is formed when:– A join condition is omitted– A join condition is invalid– All rows in the first table are joined to all rows in the second table

• To avoid a Cartesian product always include a valid join condition in a WHERE clause.

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February 14, 2008 05:53:50

safdar

Member Since: September 2007 Contribution: 5

RE: What is Cartesian product in the SQL?

hi
we have two table emp and dept in scott user
emp have 14 rows and dept have 5 rows
if we write this query
select emp.ename emp.sal dept.dname from emp dept;
this query provide you 70 rows
this called cartesian product 14*5

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February 26, 2008 05:28:20

sampra

Member Since: February 2008 Contribution: 278

RE: What is Cartesian product in the SQL?

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