Linq表连接大全(INNER JOIN、LEFT OUTER JOIN、RIGHT OUTER JOIN、FULL OUTER JOIN、CROSS JOIN)

我们知道在SQL中一共有五种JOIN操作：INNER JOIN、LEFT OUTER JOIN、RIGHT OUTER JOIN、FULL OUTER JOIN、CROSS JOIN

1>先创建两个表Group、User，两表的关系是N:N

Sql:
SELECT [t0].[GroupName], [t1].[UserName]
FROM [Group] AS [t0], [User] AS [t1]

Linq to Sql:
from g in Groups
from u in Users
select new { GroupName=g.GroupName, UserName=u.UserName}

Lambda:
Groups.SelectMany
(
g => Users,
(g, u) =>
new
{
GroupName = g.GroupName,
UserName = u.UserName
}
)

笛卡儿积(cross join)