基于临时列加入
Join based on temp column
我有两个 table 需要连接,但唯一相似的列有多余的数据需要删除。我只想修改 tables,但我只有对它们的读取权限。因此,我从 table 中删除了不需要的文本并添加了一个临时列,但我无法加入它。我收到错误:
Invalid column name '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
最简单的方法是将其包装在 CTE 中。另外,be careful using NOLOCK,除非你有明确的理由。
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;
我有两个 table 需要连接,但唯一相似的列有多余的数据需要删除。我只想修改 tables,但我只有对它们的读取权限。因此,我从 table 中删除了不需要的文本并添加了一个临时列,但我无法加入它。我收到错误:
Invalid column name '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
最简单的方法是将其包装在 CTE 中。另外,be careful using NOLOCK,除非你有明确的理由。
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;