How to avoid duplicate records in SQL

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1.73/5 (4 votes)

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SQL-Server-2008

Hi,

I have a table with columns FirstName, LastName and Age.
And I'm having one record with details Tom, Cruise and 25 in respective columns.
If I try to insert another record with same details. It should not be inserted as it is a duplicate record.
How to achieve it?

Thank you

Posted 8-Jan-13 19:33pm

Dee_Bee

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__TR__ 9-Jan-13 1:38am

You can use triggers to achieve this.

4 solutions

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pranathis012 · Answer 1 · 2013-01-08T20:05:00

HI,

This can achive in so many way's.

1) In DataBase side you set the constraints.
2) In page wise u call the SP whatever you store in table u call the firstname,secondname,and age that information to be stored in one datatable and check the count is > 0 means no need to insert ==0 means you do inserting query.

Sandeep Mewara · Answer 2 · 2013-01-08T19:41:00

Solution 2

Have a read on SQL Check Constraints.

Read:
MSDN: SQL CHECK Constraints[^]
W3S: SQL CHECK Constraint - 2[^]

Instead of having any logic in query to handle it, you can have check constraints in place and go ahead smoothly. Other way would be to handle it in UI itself before the operation.

Posted 8-Jan-13 19:41pm

Sandeep Mewara

Updated 8-Jan-13 19:42pm

v2

*Suvabrata Roy* · Answer 3 · 2013-01-08T19:36:00

Solution 1

Hi,

Add validation before insert or Add Unique Index (Non Cluster) Or constrain
http://msdn.microsoft.com/en-us/library/ms188258.aspx

Posted 8-Jan-13 19:36pm

Suvabrata Roy

Updated 27-Feb-13 18:22pm

v2

Comments

Sandeep Mewara 9-Jan-13 1:39am

For an insertion of data? Sorry, Nopes!

Khorshed Alam, Dhaka · Answer 4 · 2013-02-28T01:02:00

Create an unique index like below:

SQL

CREATE UNIQUE INDEX IX_FirstName_LastName_Age ON [TableName] (FirstName, LastName, Age)

But this is not the preferred approach, you need to have a primary key in this table that will like (let's assume you are working with patient) PatientId,FirstName, LastName and Age and PatiendId will be the primary key which will maintain uniqueness of the table.

How to avoid duplicate records in SQL

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