How can I know if an SQLexception was thrown because of foreign key violation?

Question

I want to tell the user that a record was not deleted because it has child data, but how can I be sure that the exception was thrown because of a foreign key violation? I see that there a sqlexception class that is used for all sql exception.

Answer 1

Assume you're using SQL Server.

Using teh web archive - https://web.archive.org/web/20190120182351/https://blogs.msdn.microsoft.com/tomholl/2007/08/01/mapping-sql-server-errors-to-net-exceptions-the-fun-way/

try {     # SQL Stuff } catch (SqlException ex) {     if (ex.Errors.Count > 0) // Assume the interesting stuff is in the first error     {         switch (ex.Errors[0].Number)         {             case 547: // Foreign Key violation                 throw new InvalidOperationException("Some helpful description", ex);                 break;             case 2601: // Primary key violation                 throw new DuplicateRecordException("Some other helpful description", ex);                 break;             default:                 throw new DataAccessException(ex);         }     }  } 

Case 547 is your man.

UPDATE The above is sample code and should not be used. Please follow the link as to explain why.