karen_er30
2010-10-11 06:26 PM
string query3 = "Select Sum (totalout * unitcost) from [Inventory]";
SqlCommand command3 = new SqlCommand(query3, Connection);
SqlDataReader reader3 = command3.ExecuteReader();
reader3.Read();
double num3 = System.Convert.ToDouble(reader3.GetInt32(0));
reader3.Close();
出现以下error：
InvalidCastException was unhandled by user code
Specified cast is not valid.
哪里出了问题？
SqlCommand command3 = new SqlCommand(query3, Connection);
SqlDataReader reader3 = command3.ExecuteReader();
reader3.Read();
double num3 = System.Convert.ToDouble(reader3.GetInt32(0));
reader3.Close();
出现以下error：
InvalidCastException was unhandled by user code
Specified cast is not valid.
哪里出了问题？
