How can I restrict a column to have only a fixed number of duplicate values

Question

Lets say I have a table tblPerson with below values. And In Name field I don't want the names to get repeated more than 2 times.

ID  Name
1   JOHN HONAY
2   PETER CAM
3   JOHN HONAY

So If I try to insert a new row in tblPerson with Name as "JOHN HONAY". It should throw error. How can I achieve this. Can I do something during the creation of table itself?

There is a truly [**ugly** way to do it](http://stackoverflow.com/questions/23510713/enforce-maximum-number-of-child-rows) but I'd generally advise against it. — Damien_The_Unbeliever, Jun 17 '16 at 09:28

Abdelrahman M. Allam · Answer 1 · 2016-06-17T13:30:17.360

2

I think of

On insert/ on update Triggers to check how many times the value is exists in database
Make your BL (Business logic) check for the duplicate

edited Jun 17 '16 at 13:30

answered Jun 17 '16 at 09:31

Abdelrahman M. Allam

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10
16

Don't forget to include an `update` trigger to handle duplicates created as a result of name changes. – HABO Jun 17 '16 at 13:07

How can I restrict a column to have only a fixed number of duplicate values

1 Answers1