Code for checking the same data present in table column

Question

I am facing a problem, that in my customer info table the customer id, contact no & E-mail address should not be same for two or more customers.I also have set custmomerid a

Answer 1

If i understood correctly, you need to prevent duplicate entries on customerID, contactNo and Email. The most straight forward answer is put the primary key on all three columns. This would throw a DuplicateRecord Exception when adding a record that already exists and you should properly catch it.

Another way is to check in the query (with execute scalar):

"IF EXISTS(select 1 from customer_info where customerID = ... and contactNo = ... and email = ...)

BEGIN select -1 RETURN END

insert into Customer_Info values('.......... (your query)"

Hope that helps