我需要将 sql 查询转换为 Linq to SQL 查询,但我无法得到我期望的结果:我有 2 个表,Base,M 表
BaseOne
{
MID (FK) , points to M
MChildID(FK, Nullable), points to M
}
M {
ID(PK)
}
简化选择:
SELECT * from BaseOne as f
LEFT JOIN M as m ON ISNULL(f.MChildID, f.MID) = m.ID
我试过这个:
from f in BaseOne
from m in M.Where(function(x) If(f.MChildID.HasValue,x.ID.Equals(f.MChildID.Value),x.ID.Equals(f.MID.Value))).DefaultIfEmpty
它生成了这个 SQL:
...
(CASE
WHEN [t0].[MID] IS NOT NULL THEN
(CASE
WHEN [t1].[ID] = ([t0].[MID]) THEN 1
WHEN NOT ([t1].[ID] = ([t0].[MID])) THEN 0
ELSE NULL
END)
ELSE
(CASE
WHEN [t1].[ID] = ([t0].[MChildID]) THEN 1
WHEN NOT ([t1].[ID] = ([t0].[MChildID])) THEN 0
ELSE NULL
END)
END)) = 1
LEFT OUTER JOIN ...
我遵循了这些说明,但这个例子并不是我尝试做的。
有什么建议么?