[英]Join based on temp column
I have two tables that need to be joined, but the only similar column has excess data that needs to be stripped. 我有两个需要连接的表,但是唯一类似的列具有需要删除的多余数据。 I would just modify the tables, but I only have read access to them.
我只是修改表,但是我只有它们的读取权限。 So, I strip the unneeded text out of the table and add a temp column, but I cannot join to it.
因此,我从表中删除了不需要的文本并添加了一个临时列,但我无法加入其中。 I get the error:
我得到错误:
Invalid column name 'TempJoin'
无效的列名“ TempJoin”
SELECT
CASE WHEN CHARINDEX('- ExtraText',a.Column1)>0 THEN LEFT(a.Column1, (CHARINDEX('- ExtraText', a.Column1))-1)
WHEN CHARINDEX('- ExtraText',a.Column1)=0 THEN a.Column1
END AS TempJoin
,a.Column1
,b.Column2
FROM Table1 as a
LEFT JOIN Table2 as b WITH(NOLOCK) ON b.Column2=TempJoin
Easiest way would be to wrap this in a CTE. 最简单的方法是将其包装在CTE中。 Also, be careful using NOLOCK , unless you have an explicit reason.
另外,除非有明确的原因,否则请小心使用NOLOCK 。
WITH cte AS (
SELECT
CASE WHEN CHARINDEX('- ExtraText',a.Column1) > 0
THEN LEFT(a.Column1, (CHARINDEX('- ExtraText', a.Column1))-1)
WHEN CHARINDEX('- ExtraText',a.Column1) = 0
THEN a.Column1
END AS TempJoin,
a.Column1
FROM Table1 AS a
)
SELECT *
FROM cte
LEFT JOIN Table2 AS b WITH(NOLOCK) ON b.Column2 = TempJoin;
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