.NET餐厅管理系统user数据帮助类判断是否存在管理员、判断管理员密码是否正确、判断用户是否存在、判断用户密码是否正确、查找管理员姓名

 SqlDBHelper db = new SqlDBHelper();
        #region//判断是否存在管理员
        ///

        /// 判断是否存在管理员
        ///

        ///
        ///
        public bool A_IsExist(string aid)
        {
            string sql = "select * from Admin where AID='" + aid + "'";
            return db.YNExistData(sql);
        }
        #endregion
        #region//判断管理员密码是否正确
        ///

        /// 判断管理员密码是否正确
        ///

        ///
        ///
        ///
        public bool A_IsExist(string aid, string apsw)
        {
            string sql = "select * from Admin where AID='" + aid + "' and APsw='" + apsw + "'";
            return db.YNExistData(sql);
        }
        #endregion
        #region//判断用户是否存在
        ///

        ///判断是否存在用户
        ///

        ///
        ///
        public bool U_IsExist(string userId)
        {
            string sql = "select * from Customer where CID='" + userId + "'";
            return db.YNExistData(sql);
        }
        #endregion
        #region//判断用户密码是否正确
        ///

        /// 判断密码是否正确
        ///

        ///
        ///
        ///
        public bool U_IsExist(string userId, string password)
        {
            string sql = "select * from Customer where CID='" + userId + "' and CPsw='" + password + "'";
            return db.YNExistData(sql);
        }
        #endregion
        #region//查找管理员姓名
        ///

        /// 查找管理员姓名
        ///

        ///
        ///
        public string GetAName(string aid)
        {
            string sql = "select AName from Admin where AID='" + aid + "'";
            return db.GetSingleVal(sql);
        }
        #endregion