check for unique value for a column in two tables

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i have to work on a program where two table having an email column now i have to work on to keep email value unique for both tables for insert and for update also
please help
thank in advance

Posted 19-Jun-12 22:04pm

naren programmers

Updated 19-Jun-12 22:05pm

v2

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OriginalGriff · Answer 1 · 2012-06-19T22:18:00

Do you mean that you have two separate tables, each with an email address, which may not be repeated in the other table?
If so, then just check the count of entries in the other table:

SQL

SELECT COUNT(email) FROM OtherTable WHERE email=ToBeInsertedEmailAddress

If it's zero, you can do it.

If that isn't what you mean, please explain a bit more clearly!

NaveenNeo · Answer 2 · 2012-06-19T22:29:00

Solution 4

SQL

IF (EXISTS(SELECT email FROM dbo.email WHERE email = 'user2@email.in'))
BEGIN
PRINT 'Email is already there';
END
ELSE
BEGIN
      INSERT INTO dbo.email(email,name)
      VALUES ('user2@email.in','user2');
END

Posted 19-Jun-12 22:29pm

NaveenNeo

vyas_pratik20 · Answer 3 · 2012-06-19T22:16:00

Solution 1

hi ,

you can use insert and update trigger to fix this issue bellow links will help you out
1
1)http://www.sqlteam.com/article/an-introduction-to-triggers-part-i
2)http://msdn.microsoft.com/en-us/library/aa258254(v=sql.80).aspx

Posted 19-Jun-12 22:16pm

vyas_pratik20

bhagirathimfs · Answer 4 · 2012-06-19T22:19:00

Solution 3

While creating the tables make the email column as Unique so that user can't insert same value to that column.
If you want to implement manually than before every insertion or update check that is that value is already present or not.

Posted 19-Jun-12 22:19pm

bhagirathimfs

Comments

naren programmers 20-Jun-12 4:26am

the application which i got there is a user table and employer table both have a email column the field should not be the same as this is an email , i can not convert these table to one table and then apply unique constraint as the application is at its final stage

bhagirathimfs 20-Jun-12 5:10am

See Solution 4