Question

这是提出问题的简化表：

      Names
+------+----------+
|  id  |   name   |
|------+----------|
|  1   |  Alex    |
|      |          |
|  2   |  John    |
|      |          |
|  3   |  Fred    |
|      |          |
|  4   |  Andy    |
+------+----------+

id: primary key

如何只执行单查询并获取两个名称？我有两个ID n1和n2，我想检索两个相应的名称：

SELECT name1, name2 FROM names WHERE ...n1....n2...

执行n1=2和n2=3的查询后，结果应为：

+------------+------------+
|   name1    |   name2    |
+------------+------------+
|   John     |   Fred     |
+------------+------------+

有可能吗？我不知道。

Answer 1

您可以将聚合函数与CASE表达式一起使用：

select
  max(case when id = 2 then name end) Name1,
  max(case when id = 3 then name end) Name2
from names;

请参阅Demo

Answer 2

直截了当，但必须执行两个子选择：

SELECT
(SELECT Name FROM Names WHERE ID = 2) as Name1,
(SELECT Name FROM Names WHERE ID = 3) as Name2

Answer 3

SELECT（SELECT Name FROM names WHERE ID = 1），（SELECT Name FROM Names WHERE ID = 2）FROM DUAL

Answer 4

您可以使用子选择：
SELECT（SELECT name FROM Names WHERE id = 1）AS name1，（SELECT name FROM Names WHERE id = 2）AS name2

Answer 5

我希望我理解这似乎很简单：

SELECT `name` FROM `names` WHERE `id` = '1' OR `id` = '2' LIMIT 2

两个结果在一个查询中

5 个答案: