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我試圖在Postgres的這個查詢使用別名,但Postgres的停止和抱怨錯誤:列「分類彙總」不存在列別名爲計算值
SELECT SUM(price) AS subtotal,
subtotal * 3.0 AS fees,
(subtotal + fees) AS total
FROM cart
不能使用的別名的一部分你的下一個專欄?
我試圖在Postgres的這個查詢使用別名,但Postgres的停止和抱怨錯誤:列「分類彙總」不存在列別名爲計算值
SELECT SUM(price) AS subtotal,
subtotal * 3.0 AS fees,
(subtotal + fees) AS total
FROM cart
不能使用的別名的一部分你的下一個專欄?
不,你不能再次使用相同的SQL語句中列別名 - 使用:
SELECT SUM(t.price) AS subtotal,
SUM(t.price) * 3.0 AS fees,
SUM(t.price + fees) AS total
FROM CART t
您可以參考列別名在ORDER BY子句中,一些數據庫也支持在GROUP BY
引用和HAVING
條款。
問題有關的答案:
SELECT SUM(t.price) AS subtotal,
SUM(t.price) * 3.0 AS fees,
SUM(t.price + fees) AS total
FROM CART t
豈不是下面的,如果你不能在同一個SQL語句中重複使用列別名:
SELECT SUM(t.price) AS subtotal,
SUM(t.price) * 3.0 AS fees,
SUM(t.price + (t.price * 3.0)) AS total
FROM CART t