Question

考虑以下SQL查询和响应：

CREATE TEMPORARY TABLE dreams (name text, type text);
INSERT INTO dreams VALUES ('Monkey', 'nice');
INSERT INTO dreams VALUES ('Snake', 'Not nice');
INSERT INTO dreams VALUES ('Donkey', 'nice');
INSERT INTO dreams VALUES ('Bird', 'nice');

SELECT name from dreams WHERE type='nice' ORDER BY name;
  name
--------
 Bird
 Donkey
 Monkey
(3 rows)

为方便起见，我想按照外观的顺序列举结果，无论是否有任何现有ID。预期的结果应该是a-la：

SELECT <magic_enumeration>, name from dreams WHERE type='nice' ORDER BY name;

 magic_enumeration |  name
-------------------+--------
 1                 | Bird
 2                 | Donkey
 3                 | Monkey
(3 rows)

如何根据外观顺序枚举查询结果？

Answer 1

尝试使用row_number，这是一个窗口函数

SELECT row_number() OVER (ORDER BY name) sid, <-- magic enumeration!
       name 
  FROM dreams 
  WHERE type='nice' 
  ORDER BY name;

PostgreSQL：枚举SQL查询结果

1 个答案: