Question

how to catch sql exception with its error code(error no) to identify which exception is exactly thrown in c# ?
for example database is offline or there is reference row in other table so sql wont allow me to delete row but how exactly i could identify what is the problem in catch so that i can display message to the user in my application

Answer 1

You need to put your database code into a try ... catch block, and (assuming you’re using ADO.NET against SQL Server) then catch the SqlException.

try
{
   // your database code here
}
catch(SqlException sqlEx)
{ 
   foreach(SqlError error in sqlEx.Errors)
   {
       // you can inspect the individual errors, their code etc. here
   }
}

The SqlException object will contain a collection of SqlError objects that describe the error that happened in great detail – with line number, error code and everything.

Other databases will have similar constructs – check your docs!