三层 增删改查 分页 泛型基类

   /// <summary>
    /// DAL基类
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public abstract class BaseDAL<T> where T : class, new()
    {
        /// <summary>
        /// 获取单一模型
        /// </summary>
        /// <param name="t">模型对象</param>
        /// <returns></returns>
        public T GetModel(T t)
        {
            string sql = GetSQLstr(t, "model");
            SqlParameter[] sp = GetSqlParameter(t);
            DataTable dt = SQLHelperNew.ExecuteDataTable(sql, sp);
            if (dt.Rows.Count > 0)
            {
                return DataTableToModel(dt.Rows[0]);
            }
            else
            {
                return new T();
            }

        }
        /// <summary>
        /// 获取模型集合
        /// </summary>
        /// <param name="pageindex">当前页</param>
        /// <param name="pageSize">每页条数</param>
        /// <param name="orderStr">排序字符</param>
        /// <returns></returns>
        public List<T> GetModelList(T t, int pageindex, int pageSize, string orderStr)
        {
            string sql = GetSQLstrList(t, pageindex, pageSize, orderStr);
            SqlParameter[] sp = GetSqlParameter(t);
            DataTable dt = SQLHelperNew.ExecuteDataTable(sql, sp);
            if (dt.Rows.Count > 0)
            {
                return DataTableToModelList(dt);
            }
            else
            {
                return new List<T>();
            }

        }

        /// <summary>
        /// 添加模型
        /// </summary>
        /// <param name="t">模型对象</param>
        /// <returns></returns>
        public int AddModel(T t)
        {
            string sql = GetSQLstr(t, "add");
            SqlParameter[] sp = GetSqlParameter(t);
            return SQLHelperNew.ExecuteNonQuery(sql, sp);
        }
        /// <summary>
        /// 删除模型
        /// </summary>
        /// <param name="t">模型对象</param>
        /// <returns></returns>
        public int DeleteModel(T t)
        {
            string sql = GetSQLstr(t, "delete");
            SqlParameter[] sp = GetSqlParameter(t);
            return SQLHelperNew.ExecuteNonQuery(sql, sp);
        }
        /// <summary>
        /// 修改模型
        /// </summary>
        /// <param name="t">模型对象</param>
        /// <returns></returns>
        public int EditModel(T t)
        {
            string sql = GetSQLstr(t, "edit");
            SqlParameter[] sp = GetSqlParameter(t);
            return SQLHelperNew.ExecuteNonQuery(sql, sp);
        }
        /// <summary>
        /// 获取最大条数
        /// </summary>
        /// <param name="t">模型对象</param>
        /// <returns></returns>
        public int GetModelMaxCount(T t)
        {
            string sql = GetSQLstr(t, "max");
            SqlParameter[] sp = GetSqlParameter(t);
            return (int)SQLHelperNew.ExecuteScalar(sql, sp);
        }

        /// <summary>
        /// 根据数据表返回模型集合
        /// </summary>
        /// <param name="dt"></param>
        /// <returns></returns>
        public abstract List<T> DataTableToModelList(DataTable dt);
        /// <summary>
        /// 根据数据表返回模型
        /// </summary>
        /// <param name="dt"></param>
        /// <returns></returns>
        public abstract T DataTableToModel(DataRow dt);
        /// <summary>
        /// 返回SQL语句
        /// </summary>
        /// <returns></returns>
        public abstract string GetSQLstr(T t, string type);
        /// <summary>
        /// 返回SQL语句参数
        /// </summary>
        /// <param name="t">模型</param>
        /// <returns></returns>
        public abstract SqlParameter[] GetSqlParameter(T t);

        /// <summary>
        /// 返回SQL语句
        /// </summary>
        /// <param name="sql">SQL语句</param>
        /// <param name="t">模型</param>
        /// <returns></returns>
        protected abstract string CreateSQL(string sql, T t, string type);

        /// <summary>
        /// 获取 分页SQL字符串
        /// </summary>
        /// <param name="t">模型</param>
        /// <param name="pageindex">起始项</param>
        /// <param name="pageSize">每页条数</param>
        /// <param name="orderStr">排序字符</param>
        /// <returns></returns>
        public abstract string GetSQLstrList(T t, int pageindex, int pageSize, string orderStr);
    }
}