Linq实现sql一张表数据不存在另外一张表

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Linq中包含查询

//Linq代码：
T_WxMaterials.Where(n=>T_VideoMsgs.Select(m=>m.MediaID).Contains(n.MediaID)) 

//生成的sql语句:
SELECT [t0].[ID], [t0].[Type], [t0].[Title], [t0].[Cnt], [t0].[MediaID], [t0].[LocalPath], [t0].[WxPath]
FROM [T_WxMaterial] AS [t0]
WHERE EXISTS(
    SELECT NULL AS [EMPTY]
    FROM [T_VideoMsg] AS [t1]
    WHERE [t1].[MediaID] = [t0].[MediaID]
    )

Linq中不包含查询

//Linq代码：
T_WxMaterials.Where(n=>!T_VideoMsgs.Select(m=>m.MediaID).Contains(n.MediaID)) 

//生成的sql语句:
SELECT [t0].[ID], [t0].[Type], [t0].[Title], [t0].[Cnt], [t0].[MediaID], [t0].[LocalPath], [t0].[WxPath]
FROM [T_WxMaterial] AS [t0]
WHERE NOT (EXISTS(
    SELECT NULL AS [EMPTY]
    FROM [T_VideoMsg] AS [t1]
    WHERE [t1].[MediaID] = [t0].[MediaID]
    ))