查询 select 不同顺序的问题

Question

在问题的帮助下，我学会了如何将 SELECT DISTINCT 与 ORDER BY 一起使用：
How to use DISTINCT and ORDER BY in same SELECT statement?

我从这个问题中学会了使用 ORDER BY CASE：
How do I return rows with a specific value first?

但是我有一个很难写的查询：

我有一个 table CUSTOMER 列 NAME，我想得到所有 distinct 客户的名字，我想找到名字'Hamza'先.

SELECT DISTINCT "CUSTOMER"."NAME",
    Max("CUSTOMER"."NAME")
FROM "CUSTOMER"
WHERE
    "CUSTOMER".id >= 2
GROUP BY "CUSTOMER"."NAME"
ORDER BY CASE WHEN ("CUSTOMER"."NAME" = 'HAMZA' ) THEN 1 ELSE 2 END

错误:

ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list
LINE 15: ORDER BY CASE WHEN ("CUSTOMER"."NAME" = 'HAMZA' ) THEN 1 EL...
_________________.^
SQL state: 42P10
Character: 372

编辑

已解决：

SELECT "CUSTOMER"."NAME", -- distinct keyword removed here
    Max("CUSTOMER"."NAME")
FROM "CUSTOMER"
WHERE
    "CUSTOMER".id >= 2
GROUP BY "CUSTOMER"."NAME"
ORDER BY
CASE WHEN ("CUSTOMER"."NAME" = 'HAMZA' ) THEN 1 ELSE 2 END,
CASE WHEN ("CUSTOMER"."NAME" = 'GIORNO' ) THEN 1 ELSE 2 END

Answer 1

分组将确保您获得不同的客户名称。只需删除此修饰符，您应该没问题：

SELECT "CUSTOMER"."NAME", -- distinct keyword removed here
    Max("CUSTOMER"."NAME")
FROM "CUSTOMER"
WHERE
    "CUSTOMER".id >= 2
GROUP BY "CUSTOMER"."NAME"
ORDER BY CASE WHEN ("CUSTOMER"."NAME" = 'HAMZA' ) THEN 1 ELSE 2 END

Answer 2

I want to get all the distinct names of the customers, and I want to find name 'Hamza' first.

为什么不这样做呢？

SELECT "CUSTOMER"."NAME"
FROM "CUSTOMER" 
GROUP BY "CUSTOMER"."NAME" 
ORDER BY ("CUSTOMER"."NAME"  = 'Hamza') DESC

将SELECT DISTINCT与聚合函数一起使用通常只会混淆查询逻辑。

我也不知道你为什么选择两次这个名字。

查询 select 不同顺序的问题

Trouble with query select distinct order by case

sql

postgresql

select

distinct