You use Microsoft Visual Studio 2010 and Microsoft .NET Framework 4.0 to create an application.
The application connects to a Microsoft SQL Server database.
You write the following code segment that executes two commands against the database within a transaction.
(Line numbers are included for reference only.)
01 using(SqlConnection connection = new SqlConnection(cnnStr)) {
02 connnection.Open();
03 SqlTransaction sqlTran = connection.BeginTransaction();
04 SqlCommand command = connection.CreateCommand();
05 command.Transaction = sqlTran;
06 try{
07 command.CommandText = INSERT INTO Production.ScrapReason(Name) VALUES(Wrong size);
08 command.ExecuteNonQuery();
09 command.CommandText = INSERT INTO Production.ScrapReason(Name) VALUES(Wrong color);
10 command.ExecuteNonQuery();
11 …
l2 }
You need to log error information if the transaction fails to commit or roll back. Which code segment should you insert at line 11?
A.
sqlTran.Commit();
}
catch (Exception ex) {
sqlTran.Rollback();
Trace.WriteLine(ex.Message);
}
B.
sqlTran.Commit();
}
catch (Exception ex) {
Trace.WriteLine(ex.Message);
try {
sqlTran.Rollback();
}
catch (Exception exRollback) {
Trace.WriteLine(exRollback.Message);
}
}
C.
catch (Exception ex){
Trace.WriteLine(ex.Message);
try{
sqlTran.Rollback();
}
catch (Exception exRollback){
Trace.WriteLine(exRollback.Message);
}
}
finaly {
sqltran.commit( );
}
D.
catch (Exception ex) {
sqlTran.Rollback();
Trace.WriteLine(ex.Message);
}
finaly {
try {
sqltran.commit( );
}
catch (Exception exRollback) {
Trace.WriteLine(excommit.Message);
}
}
Explanation:
A would work, but B is better since we are checking for possible errors during the rollback. C & D would try to do a rollback before a commit?
The finally block is only executed when the application ends, which may not be the appropriate place to put this logic.
Normally, a finally block would contain code to close a Database connection. The finally block executes even if an exception arises.