Coding Error

Question

Sir I have problems in executing my pages with sqlserver 2008 while saving and updating the data i got an error as below in the code of line:
 a= cm.ExecuteNonQuery();
The error is String or binary data would be truncated.
The statement has been terminated.
How can I resolve it. I am sending you the whole project with backup file of database.In it to logged in with the login page ,the loginname =SHESH and password =123 .Please sir give me the proper solution to the error