我有2个表:一个表具有一个nvarchar列,其格式如下:“ Type | Id(或GUID)”。如果列的类型是“ Table2”,而第二部分是整数,则table是具有在第一个表中引用的主键。
所以我第一次尝试加入表格是:
var query = from t1 in db.Table1
join t2 in db.Table2
on t1.TypeAndId equals "Table1|" + t2.Id
select t2;
但这需要永远执行。在分析器中签入查询会生成类似以下内容的
: SELECT
[Extent2].[Id] AS [Id]
FROM [dbo].[Table1] AS [Extent1]
INNER JOIN [dbo].[Table2] AS [Extent2] ON [Extent1].[TypeAndId] = (N'Type|' + CAST( [Extent2].[Id] AS nvarchar(max)))
WHERE [Extent1].[Id] = @p__linq__0
我们的DBA建议如下:
SELECT
[Extent2].[Id] AS [Id]
FROM [dbo].[Table1] AS [Extent1]
INNER JOIN [dbo].[Table2] AS [Extent2] ON replace([Extent1].[TypeAndId],'Type|','') = [Extent2].[Id]
WHERE [Extent1].[Id] = 519
因此,显而易见的解决方案是:
var query = from t1 in db.Table1
join t2 in db.Table2
on t1.TypeAndId.Replace("Table1|", "") equals t2.Id
select t2;
但是,由于一列为nvarchar,另一列为int,因此无法编译。因此,我想知道如何进行联接以生成由数据库管理员建议的查询