SQL 條件表達式 MS Access 中的數據類型不匹配

Question

我有個問題。

當我嘗試運行此查詢時：

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*'

它說：

“條件表達式中的數據類型不匹配”

現在我已經知道它必須與第一個和最后一個查詢有關。 這兩個一起導致了錯誤。

我究竟做錯了什么？

Answer 1

您可以通過在第一個查詢中為NULL提供適當的類型來解決此問題：

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*'

實際上，我不確定正確的類型是什么。 我只是猜測。