linq join on 多条件查询

[菜鸟6号]

select * FROM table1
JOIN table2
ON table1.MzRegId = table2.ID
JOIN table3
ON ( table1.MzRegId = table3.MzRegId
OR table2.CardNo = table3.CardNo )

怎么把上面的sql 语句转换为 linq

[q107770540]

linq对INNER JOIN的转化，是不支持OR的，但支持多个AND 你的情况可以用存储过程封装后在LINQ内调用

[threenewbee]

from x in table1
join y in table2 on x.MzRegId equals y.ID
join z in table3 on new { a = x.MzRegId, b = y.CardNo } equals new { a = z.MzRegId, b = z.CardNo }
select new { x, y, z }

[菜鸟6号]

引用 1 楼 caozhy 的回复:

from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on new { a = x.MzRegId, b = y.CardNo } equals new { a = z.MzRegId, b = z.CardNo } select new { x, y, z }

你看清楚了， “ OR ” table2.CardNo = table3.CardNo 这里用的or 不是用and连接的

[threenewbee]

引用 2 楼 vipleft 的回复:

[quote=引用 1 楼 caozhy 的回复:] from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on new { a = x.MzRegId, b = y.CardNo } equals new { a = z.MzRegId, b = z.CardNo } select new { x, y, z }

你看清楚了， “ OR ” table2.CardNo = table3.CardNo 这里用的or 不是用and连接的[/quote] or更简单，可以这么写 (from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on x.MzRegId equals z.MzRegId select new { x, y, z }).Union (from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on y.CardNo equals z.CardNo select new { x, y, z })

[菜鸟6号]

引用 3 楼 caozhy 的回复:

[quote=引用 2 楼 vipleft 的回复:] [quote=引用 1 楼 caozhy 的回复:] from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on new { a = x.MzRegId, b = y.CardNo } equals new { a = z.MzRegId, b = z.CardNo } select new { x, y, z }

你看清楚了， “ OR ” table2.CardNo = table3.CardNo 这里用的or 不是用and连接的[/quote] or更简单，可以这么写 (from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on x.MzRegId equals z.MzRegId select new { x, y, z }).Union (from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on y.CardNo equals z.CardNo select new { x, y, z })[/quote] 用Union查询太复杂了，我贴出来的只是一部分，还有一大堆东西，到时写好后可读性就太低了

[菜鸟6号]

引用 4 楼 vipleft 的回复:

[quote=引用 3 楼 caozhy 的回复:] [quote=引用 2 楼 vipleft 的回复:] [quote=引用 1 楼 caozhy 的回复:] from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on new { a = x.MzRegId, b = y.CardNo } equals new { a = z.MzRegId, b = z.CardNo } select new { x, y, z }

你看清楚了， “ OR ” table2.CardNo = table3.CardNo 这里用的or 不是用and连接的[/quote] or更简单，可以这么写 (from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on x.MzRegId equals z.MzRegId select new { x, y, z }).Union (from x in table1 join y in table2 on x.MzRegId equals y.ID join z in table3 on y.CardNo equals z.CardNo select new { x, y, z })[/quote] 用Union查询太复杂了，我贴出来的只是一部分，还有一大堆东西，到时写好后可读性就太低了[/quote] 还有没有更好的办法？？

[threenewbee]

如果你想写得简单，但是不在乎性能，你可以写 from x in table1 join y in table2 on x.MzRegId equals y.ID from z in table3 x.MzRegId == table3.MzRegId || y.CardNo == z.CardNo select new { x, y, z } 在table3数据量大的时候性能会比较差，反之无所谓。 或者你干脆用sql。