topic Re: cardinality? in Application Development and Automation Discussions

cardinality?

Former Member — Mon, 25 Jun 2007 09:26:18 GMT

what is the cardinality

what is its function

and what is it use?

can any one give , with an example for cardinality?

Re: cardinality?

Former Member — Mon, 25 Jun 2007 09:35:24 GMT

Hi,

Cardinality indicates the primary and foriegn key ratio.

For example if cardinality is 1:1 , then for one record in check table ( Primary key ) there should be one record in dependent table.

Like wise 1:N indicates , for one record in check table , dependent table can have N records.

Thanks

Re: cardinality?

Former Member — Mon, 25 Jun 2007 09:35:43 GMT

Hi,

Jus go thro this notes below.

Cardinality

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 side (n) of the cardinality is 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.

The right side (m) of the cardinality is defined as follows:

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.

*****Reward points if helpful.

All the best

Re: cardinality?

Former Member — Mon, 25 Jun 2007 09:46:27 GMT

The left side (n) of the cardinality is defined as follows:

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

The right side (m) of the cardinality is defined as follows:

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.

<b>A foreign key describes a relationship between two tables. You can define this relationship more precisely by specifying the cardinality and type of foreign key fields</b>.

<b>The following types of foreign key field can be defined:</b>

1.No key fields/candidates: The foreign key fields are neither primary key fields of the foreign key table nor do they uniquely identify a record of the foreign key table (key candidates). For this reason, the foreign key fields do not (partially) identify the foreign key table.

2.Key fields/candidates: The foreign key fields are either primary key fields of the foreign key table or they already uniquely identify a record of the foreign key table (key candidates). The foreign key fields therefore (partially) identify the foreign key table.

3.Key fields of a text table: The foreign key table is a text table for the check table, that is the key of the foreign key table only differs from the key of the check table in that it has an additional language key field. This is a special case of the type Key fields/candidates.

here is the example with screen shots

<a href="http://">http://help.sap.com/saphelp_nw04/helpdata/en/b2/fbb859c64611d295dd00a0c929b3c3/frameset.htm</a>

reward points if it is usefull ...

Girish

Re: cardinality?

Former Member — Mon, 25 Jun 2007 09:51:37 GMT

thanq .....

for providing me the answer...literally its good one....which is understandable.....

I'm not saying byeeee.....We'll be in touch ....................

Re: cardinality?

Former Member — Mon, 25 Jun 2007 10:05:05 GMT

Hello Mr. Lokesh,

Reward points if u find the answers useful.

Jus closing the thread with rewarding points,wil not motivate others to answer..

Anyways all the best.