how to validat the data if the data allready exist in the table record in c#?

[mani141990]

how to validat the data if the data allready exist in the table record in c#?
for example i wanted to add the studend roll no. if roll no. is 134 and if we are adding rollno. 134 student then we get the warning like roll no. 134 is allready exist

[pod]

You "addData" function should return a stringMessage

Before adding any new records,
your data layer script should perform a search for existing data.

search for existing data 
If a match is found then 
   no data will be inserted
   return a message saying "unable to add, data already exist"
else
   insert the data
   return a message insertion succesful
end

Hope this helps

P:oD