public User findUser(string loginName, string password) { string sql = @"select * from users where loginName ='" + loginName + "' and psw='" + password + "'"; DataTable table = sqlTool.query(sql); if (null == table || table.Rows.Count == 0) { return(null); } User user = null;; foreach (DataRow row in table.Rows) { user = new User(); user.Id = (int)row["id"]; user.LoginName = loginName; user.Password = password; } return(user); }