ExecuteNonQuery

ExecuteNonQuery 对于 UPDATE、INSERT 和 DELETE 语句，返回值为该命令所影响的行数。对于所有其他类型的语句，返回值为 -1。如果发生回滚，返回值也为 -1
示例：     
            SqlConnection conn = new SqlConnection(connstr);//connstr 数据库连接字符信息
            SqlCommand comm = new SqlCommand();
            comm.Connection = conn;
            comm.CommandText = "Update Training set Hours = 600 where Trainingcode = @Trainingcode";
            SqlParameter para = comm.Parameters.Add("@Trainingcode", SqlDbType.Char, 10);
            para.Value = txtTrainCode.Text;
            conn.Open();
            int numUpdated = comm.ExecuteNonQuery();//numUpdated 获取UPdate后影响的行数
            conn.Close();