MySQL:从多个表中选择数据

Question

我有 3 个订单表

订单1:

OrderNumber, TransactionID, TrackingNumber

订单2:

OrderNumber, TransactionID, TrackingNumber

订单3:

OrderNumber, TransactionID, TrackingNumber

我显示的订单总数不完整，因此我需要从 TrackingNumber = '' 的表格中进行选择

Answer 1

您需要使用UNION:

SELECT * FROM orders1 WHERE TrackingNumber = ''
UNION
SELECT * FROM orders2 WHERE TrackingNumber = ''
UNION
SELECT * FROM orders3 WHERE TrackingNumber = ''