How do I reduce duplication of data when database is remote file?

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I am creating client-server application architecture for database and local machine will access remote database file, so there is possibility of data duplication like one roll no allocated to two student

For Ex.
Machine 1 Access Table Student and insert new record number as 1
Machine 2 Access Table Student and insert new record number as 1

What I have tried:

I have given primary key to that field but it doesn't work

Posted 4-Aug-17 0:37am

Hardevsinh Mori

Updated 29-Aug-17 0:31am

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4 solutions

Solution 2

I have already faced this situation

Try to use unique or AUto increment

Posted 4-Aug-17 1:58am

Manav Pandya

Solution 3

That's strange, a PRIMARY KEY automatically has a UNIQUE constraint defined on it. See: SQL PRIMARY KEY Constraint[^]
Are you sure the users are using the same database and table ?
But it is probably best to use IDENTITY, see: SQL AUTO INCREMENT a Field[^]

Posted 6-Aug-17 1:32am

RickZeeland

Updated 6-Aug-17 1:37am

v2

Solution 4

With the help of

composite key

we can reduce the duplication when transfer data from one machine to another machine.

Posted 29-Aug-17 0:31am

Moin 10918476

Updated 29-Aug-17 19:24pm

v2

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OriginalGriff · Accepted Answer · 2017-08-04T01:09:00

Two options:
1) Use an IDENTITY field: IDENTITY (Property) (Transact-SQL) | Microsoft Docs[^] - the DB then takes control of the column and assigns values for you so that there is no duplication.
2) Use a UNIQUEIDENTIFER field: uniqueidentifier (Transact-SQL) | Microsoft Docs[^] and set it's value from your C# code via a Guid (or set the default property of the column to NEWID: NEWID (Transact-SQL) | Microsoft Docs[^] )