查询结果中有多个null列，产生的语句是错误的，请问这样的怎么解决。
代码：
return (from task in fiterTasks
select new SelectListItem()
{
ItemTitle = task.Title,
ItemTaskID = task.TaskID,
ItemPlugInSetupID = null,
Tag = null
}).Concat(
from plug in fiterPlug
select new SelectListItem()
{
ItemTitle = plug.PlugInCName,
ItemTaskID = null,
ItemPlugInSetupID = plug.ID,
Tag = plug.Tag
}
);
产生的sql：
exec sp_executesql N'SELECT COUNT(*) AS [value]
FROM (
SELECT [t0].[Title], [t0].[TaskID], @p1 AS [value]
FROM [publisher].[Task] AS [t0]
WHERE [t0].[IsEnabled] = @p0
UNION ALL
SELECT [t1].[PlugInCName], NULL AS [value], [t1].[ID] AS [value2], [t1].[Tag]
FROM [publisher].[PlugInSetup] AS [t1]
) AS [t2]',N'@p0 int,@p1 int',@p0=1,@p1=NULL
