Join - comment info confusing!

[newby]

Hello,

New to DS so would appreciate any help! I am looking at a join which has the following comment... "Performs cartesian product of the Facilty Expiry Date records with Time band codes".

Does anyone have any idea what this means?!

Thanks.

[ajith]

Hello,

New to DS so would appreciate any help! I am looking at a join which has the following comment... "Performs cartesian product of the Facilty Expiry Date records with Time band codes".

Does anyone have any idea what this means?!

Thanks.

Welcome aboard Newbie,

Cartesian product is a database concept rather than a Datastage concept so, It's not Datastage which confused you.

A cartesian product is is the result of an unrestricted join of two or more tables. ie Two or more tables are joined without any join conditions.
So if you are joining a table with 5 rows and a table with 6 rows after the join it will have 30 rows with all the possible combinations of columns in two tables.

Say, a table Employee with id and name is there and

1 a
and 2 b are the only rows it contains

Another table with only termination date is there and that is the only column it has

and let

2000-01-19
9999-12-31

are the rows contained by it

If you take a cartesian product of these tables it will look like

1 a 2000-01-19
1 a 9999-12-31
2 b 2000-01-19
2 b 9999-12-31

Hope that helps ..

Ajith

[newby]

Ajith,

That's great - thanks very much for your help!