本文介绍了FROM 中的子查询必须有别名的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个用 PostgreSQL 编写的查询，它返回一个错误说:
I have this query I have written in PostgreSQL that returns an error saying:
[错误] 错误:
第 3 行:FROM (SELECT DISTINCT (identifiant) AS made_only_recharge
[Err] ERROR:
LINE 3: FROM (SELECT DISTINCT (identifiant) AS made_only_recharge
这是整个查询:
SELECT COUNT (made_only_recharge) AS made_only_recharge
FROM (
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER = '0130'
EXCEPT
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER != '0130'
)
我在 Oracle 中有一个类似的查询，它运行良好.唯一的变化是我在 Oracle 中有 EXCEPT 我用 MINUS 关键字替换了它.我是 Postgres 的新手，不知道它要求什么.处理这个问题的正确方法是什么?
I have a similar query in Oracle that works fine. The only change is where I have EXCEPT in Oracle I have replaced it with the MINUS key word. I am new to Postgres and don't know what it is asking for. What's the correct way of handling this?
推荐答案
在子查询中添加ALIAS，
SELECT COUNT(made_only_recharge) AS made_only_recharge
FROM
(
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER = '0130'
EXCEPT
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER != '0130'
) AS derivedTable -- <<== HERE
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