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sql - 条件表达式 MS Access 中的 SQL 数据类型不匹配

问题描述

我有个问题。

当我尝试运行此查询时：

SELECT Artiesten.ID AS txtArtiestId, 
NULL AS txtAlbumId, 
NULL AS txtNummerId, 
Artiestnaam AS Artiesten, 
NULL AS Albums, 
NULL As Nummers 
FROM Artiesten 
WHERE Artiesten.Artiestnaam LIKE '*On*' 

UNION ALL

SELECT 
Artiesten.ID AS txtArtiestId, 
Albums.ID AS txtAlbumId, 
NULL AS txtNummerId, 
Artiesten.Artiestnaam AS 
Artiesten, Naam AS Albums, 
NULL As Nummers 
FROM Albums 
INNER JOIN Artiesten ON Albums.ArtiestId = Artiesten.ID 
WHERE  albums.naam LIKE '*On*'

UNION ALL

SELECT 
Artiesten.ID AS txtArtiestId, 
Albums.ID AS txtAlbumId, 
Nummers.ID AS txtNummerId, 
Artiesten.Artiestnaam AS Artiesten, 
Albums.Naam AS Albums, 
Nummers.Naam AS Nummers 
FROM  (Nummers INNER JOIN Albums ON Nummers.AlbumId = Albums.ID)
INNER JOIN Artiesten ON Albums.ArtiestId = Artiesten.ID
WHERE  Nummers.Naam LIKE '*On*'

它说：

“条件表达式中的数据类型不匹配”

现在我已经知道它必须与第一个和最后一个查询有关。这两个一起导致了错误。

我究竟做错了什么？

标签： sqlms-access

解决方案

您可以通过NULL在第一个查询中提供适当的类型来解决此问题：

SELECT Artiesten.ID AS txtArtiestId, 
       int(NULL) AS txtAlbumId, 
       int(NULL) AS txtNummerId, 
       Artiestnaam AS Artiesten, 
       str(NULL) AS Albums, 
       str(NULL) As Nummers 
FROM Artiesten 
WHERE Artiesten.Artiestnaam LIKE '*On*'

实际上，我不确定正确的类型是什么。我只是猜测。

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