[英]How to write a sql statement using union and identifying data from table a and table b
我正在嘗試編寫一個 SQL 查詢,在我使用聯合后,我想確定哪些數據來自銷售表,哪些數據來自庫存表
Select customer
, calendar date
, sales amount
, location
From Sales
Union
Select customer
, cal date
, sales price
, distribution location
From inventory
經典的方法是使用額外的列
Select 'SALES' origin,
, customer
, calendar date
, sales amount
, location
From Sales
Union
Select 'INVENTORY'
, customer
, cal date
, sales price
, distribution location
From inventory
UPD:僅供參考,“union”子句會刪除所有影響性能的重復項,因此如果不打算刪除重復項,最好使用“union all”代替
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