About Cardinality

[former_member530652]

when i put relation in cardinality for eg. 1:1 or 1:c or 1:cn like this .... but it don't show proper output while entering data on the output screen....so can you tell me why it is happening and explain me in brief about relationship used in cardinality.

[former_member530652]

when i put relation in cardinality for eg. 1:1 or 1:c or 1:cn like this .... but it don't show proper output while entering data on the output screen....so can you tell me why it is happening and explain me in brief about relationship used in cardinality.

[Former Member]

Hi Sandeep welcome to SDN,

Cardinality describes the relationship between different entities.

Have a look at the example of a family consisting of parents (woman & man or wife & husband) and children:

Relation "is married": man : woman = 1:C (meaning a man may or may not be married, but if he is married then only to a single woman)

Some cultures allow the following relation "is married": man : woman = 1:CN (meaning a man may be married to several women).

A pair (man & woman) may or may not have children, thus the relation is: man/woman : child = 1:CN

In SAP we can have sales order (VA03) containing several items. What is the cardinality between order and item?

(1) order : item = 1:CN (means an order could exist without having any item -> false)

(2) order : item = 1:N (each order must have at least a single item -> right)

The last example should show how important it is to use the right cardinality between your entities.

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Cheers,

Chaitanya.

[Former Member]

Dear Sandeep,

I have mentioned what diffrent cardinality means.

The cardinality (n:m) describes the foreign key relationship with regard to the number of possible dependent records (records of the foreign key table) or referenced records (records of the check table).

The left and right sides of the cardinality are defined as follows:

>n=1: There is exactly one record assigned to the check table for each record of the foreign key table.

>n=C: The foreign key table may contain records which do not correspond to any record of the check table because the foreign key field is empty. This can occur for example if the field of the foreign key table is optional, in which case it does not have to be filled.

>m=1: There is exactly one dependent record for each record of the check table.

>m=C: There is at most one dependent record for each record of the check table.

>m=N: There is at least one dependent record for each record of the check table.

>m=CN: There may be any number of dependent records for each record of the check table.

Best Regards,

Rajesh.

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[Former Member]

Dear Sandeep,

This is likely caused because you have data coming from multiple tables.

Also check that the primary key in one table is linked to a foreign key in the other.

Best Regards,

Rajesh

Please reward points if found helpful.