此代码抛出一个NullReferenceException
当它调用ExecuteScalar
:的ExecuteScalar引发的NullReferenceException
selectedPassengerID = 0;
//SqlCommand command = GenericDataAccess.CreateCommand();
// 2nd test
string connectionString = "";
SqlConnection conn;
connectionString = ConfigurationManager.
ConnectionStrings["ConnST-MHM"].ConnectionString;
conn = new SqlConnection(connectionString);
SqlCommand command = new SqlCommand();
command.CommandType = CommandType.StoredProcedure ;
command.Connection = conn;
command.CommandText = "SearchForPassenger";
SqlParameter param;
param = command.CreateParameter();
param.ParameterName = "@name";
param.Value = pName; // Session[""];
param.DbType = DbType.String;
command.Parameters.Add(param);
param = command.CreateParameter();
param.ParameterName = "@flightDate";
param.Value = date;
param.DbType = DbType.String;
command.Parameters.Add(param);
param = command.CreateParameter();
param.ParameterName = "@ticketNo";
param.Value = ticketNumber;
param.DbType = DbType.Int32;
command.Parameters.Add(param);
int item;
command.Connection.Open();
item = (int)command.ExecuteScalar();
检查的DBNull是至关重要的,因为它会帮助你很多,如果你可以到nulluable类型。 +1 – 2010-10-18 22:27:42