How many primary key constraints can we have in a table of ms-access?

[sivakumar mariappan]

Hi, How many primary key constraints can we have in a table of ms-access? Any other constraints available in ms-access other than primary key? Please share your ideas... Thanks, Sivakumar.M.

[Lost User]

One table, one primary key. You can verify this in the documentation[^]; "You can use the PRIMARY KEY reserved words to designate one field or set of fields in a table as a primary key. All values in the primary key must be unique and not Null, and there can be only one primary key for a table."

I are troll :)

[riced]

As Eddy said one primary key per table. But you can create indexes on non-key fields and set them to not allow duplicates. Effectively giving you a constraint that the column must contain unique values. It's also possible to allow two (or more) columns to have duplicates while the combination of the two columns is unique - again by creating an appropriate index.

Regards David R --------------------------------------------------------------- "Every program eventually becomes rococo, and then rubble." - Alan Perlis

[Niladri_Biswas]

How many primary key constraints can we have in a table of ms-access?

Ans: Only 1. Not only in MSAccess, in any database i.e. Oracle, Sql Server etc. It is a general database rule.

You can have many FK and Composite keys however.

Any other constraints available in ms-access other than primary key? Ans:

Yes.

  Primary key constraints
  Foreign key constraints
  Check constraints
  Check constraint expressions
  Unique constraints
  Default constraints

A little search in google gave me the second answer

http://office.microsoft.com/en-us/access/HP030838791033.aspx[^]

Hope it helps :)

Niladri Biswas