JoinTableAccess<T> 源码

此源码为文章“.NET框架下ORM的一个轻量高效替代方案”的组成部分。

此类的基类 ReadonlyTableAccess<T> 源码：http://www.cnblogs.com/wfyfngu/archive/2010/01/28/1658374.html

using System;
using System.Collections.Generic;
using System.Text;

namespace FunTonn.MySqlDAL.SqlUtility {

    /// <summary>
    /// 提供一个抽象类，提供对2个表的连接访问
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public abstract class JoinTableAccess<T> : ReadonlyTableAccess<T> {

        protected const char MAIN_TABLE_ALIAS = 'm';
        protected const char SUB_TABLE_ALIAS = 's';

        /// <summary>
        /// 获取主表访问对象
        /// </summary>
        abstract internal IReadonlyTableAccess MainTableDAL { get;}

        /// <summary>
        /// 获取子表访问对象
        /// </summary>
        abstract internal IReadonlyTableAccess SubTableDAL { get;}

        /// <summary>
        /// 获取数据表的连接方式，如
        /// join, inner join等
        /// </summary>
        virtual protected string JoinCommand {
            get { return "join"; }
        }


        public override string TableName {
            get {
                // 将返回如下格式的字符串
                // {0}      {1} {6} {2}     {3}  {1}{4}         {3}{5}
                // maintable m join subtable s on m.primaryKey = s.primaryKey
                return string.Format(
                    "{0} {1} {6} {2} {3} on {1}.{4}={3}.{5} ",
                    MainTableDAL.TableName,
                    MAIN_TABLE_ALIAS,
                    SubTableDAL.TableName,
                    SUB_TABLE_ALIAS,
                    MainTableDAL.TablePrimaryColumn.Name,
                    SubTableDAL.TablePrimaryColumn.Name,
                    JoinCommand
                    );
            }
        }

        public override TableColumnCollection TableColumns {
            get {
                // 主表字段
                TableColumnCollection mainColumns = MainTableDAL.TableColumns;
                // 将主表字段全部加上表限定名（只能使用表别名）
                foreach (TableColumn column in mainColumns) {
                    column.Name = MAIN_TABLE_ALIAS + "." + column.Name;
                }

                // 子表字段
                TableColumnCollection subColumns = SubTableDAL.TableColumns;
                //// 删除子表的主键字段
                //subColumns.Remove(SubTableDAL.TablePrimaryColumn);
                // 将子表字段全部加上表限定名（只能使用表别名）
                foreach (TableColumn column in subColumns) {
                    column.Name = SUB_TABLE_ALIAS + "." + column.Name;
                }
                mainColumns.AddRange(subColumns);
                return mainColumns;
            }
        }

        //internal override T BuildEntity(MySql.Data.MySqlClient.MySqlDataReader reader, int startIndex) {
        //    throw new Exception("The method or operation is not implemented.");
        //}

    }
}