如何編寫查詢A（表）工會B（表）在MySQL相交C（表）

Question

蔭嘗試這樣做

select Barcode from ITList union select Barcode from Equipment_list 
intersect select Barcode from Scanneditem 

Answer 1

檢查：

SELECT a.Barcode FROM Scanneditem AS a 
JOIN (SELECT Barcode FROM ITList UNION SELECT Barcode FROM Equipment_list) AS b 
ON a.Barcode=b.Barcode; 

Answer 2

您可以使用exists此

Select * from (select Barcode from ITList union select Barcode from Equipment_list) as t 
where exists (select Barcode from Scanneditem where Scanneditem.Barcode = t.Barcode) 

Answer 3

雖然在MySQL沒有INTERSECT操作，您可以使用IN子句或EXISTS子句，這取決於o輕鬆地模擬這種類型的查詢INTERSECT查詢的複雜性。

請試試這個：

SELECT * FROM (SELECT Barcode FROM ITList UNION SELECT Barcode FROM Equipment_list) AS allbarcode 
WHERE allbarcode.Barcode IN (SELECT Barcode FROM Scanneditem) 

您還可以查看納文戈亞爾SQL與EXISTS子句（下面的回覆）。