Best way to check duplication in database in c#

Question

Hi There are many scenario in c# that we need to verify for duplication check before saving records. So I would like to know that if I have 1 database with 1 huge table filled with around 1-2 lac records say tblcustomer and if I want to check if the customer email ID in it is not duplicate then what is the best way of doing it. Pls explain with some code if possible. My .net application would be in c#  i may use ajax if required & backend would be sql server!

hj jh · Answer

thank you all for answers. But i think none of the answers are much satisfactory! Because none of this ways are much efficient as far as large database is considered. Yes I have already applied primary key to table but even after that it takes long & its not a efficient way to check for duplication in database & increase database transaction for this! I am looking for some still better solution!

Krishna Garad · Answer

You may try this in sp Create Procedure Sp_Check ( @email Varchar(20) @result Varchar(20) Out ) As Begin if Exists(Select EmailId From TableName Where EmailId=@email) Set @result='Already Available' Else Set @result='Not Available' End

Satyapriya Nayak · Answer

Hi Please refer the below links http://www.aspdotnet-suresh.com/2011/03/how-to-check-username-availability.html http://csharpdotnetfreak.blogspot.in/2012/05/check-username-email-availability-ajax.html Thanks If this post helps you mark it as answer

Sukesh Marla · Answer

if your table contains 1-2 lack records then we should think First make your column(for instance it is email id ) primary key or unique key.