skcmadduri

 Profile Answers by skcmadduri 

• May 8th, 2008

 

You need to setup cardinalities inorder to find loops and traps (fan trap & chasm trap)

garycronin

 Profile Answers by garycronin 

• May 28th, 2008

 

Moreover to effectivily use data on tables that are joined you must state the cardinality. Bobj can get it wrong sometimes so I'd advise you to set them up manually.

garycronin

 Profile Answers by garycronin 

• May 28th, 2008

 

Cardinality expresses the minimum and maximum number of instances of an entity B that can be associated with an instance of an entity A. The minimum and the maximum number of instances can be equal to 0, 1, or N. Because a join represents a bidirectional relationship, it must always have two cardinalities. If you selected the Detect cardinalities in joins options in the Database tab of the Options dialog box, Designer detects and retrieves the cardinalities of the joins. If you do not use this option, you can still retrieve the cardinalities for one or all joins in the universe. There are two main methods for detecting or editing cardinalities: the Detect Cardinalities command the Edit Join dialog box

Rajnish_kaushal

 Profile Answers by Rajnish_kaushal 

• Apr 13th, 2009

 

Main use of Cardinalities is to detect loops as said by one of member.

It is always advisable to manually assign cardinalities. Browse the database first , figure out cardinalities and then apply the same manually. BOBJ can sometime take lot of time detect cardinalities as it traverse through individual record to figure out cardinality.

Regards


Rajnish Kaushal

ASHOK1324

 Profile Answers by ASHOK1324 

• Apr 19th, 2009

 

Cardinality describes a join between 2 tables by stating how many rows of one
table will match with rows of another table. It is very important to detect join
problems and to create the contexts to correct the limitations of a target
table.

BO designer can automatically detect and set cardinalities for each join.
But, we manually check the cardinalities based on the nature of keys that are
joined.

Drag the column of first table to the corresponding column of second table or
simply go to Insert->Join to create a join between 2 tables.

You can manually change the cardinality from n-n [many to many] or 1-n or n-1
or 1-1 and Click on "Detect". In BO, It is always best to use 1-n cardinality
for fast data retrieval. Always delete the unnecessary joins which have n-n
cardinality as these joins create loops.