Question

I am working on a project in .NET (C#), connected with a database. And I am entering values in database through ‘text-box’ control, for a part of the project. What I want is to check if the user entering value already exsists in the database and if so, shows error during that time only.

I have searched for any familiar post here, that could solve my query, but didn’t get any.
Thank you.

my EXACT objective(if not cleared earlier):-

when the user enter the value in
textbox, automatically an event to
check any duplicate records in
database should occur. And if found,
displays an error message

Answer 1

A possible way to go would be to have a AJAX callback on the onchange event of the textbox and then check if the value already exists in your database table.

You could also implement it via a ServerSideValidationExtender control:

• ServerSideValidationExtender – ASP.NET Server-Side Validation via AJAX Partial Page PostBack