MySQL

Question

（抱歉，如果问题已经被问过或者太简单了）

Select 来自 table 水平 = 'High school' 且没有体育（'Soccer'、'Basketball'）科目的学生的所有唯一姓名.

ID      name    level          subject

00001   John    High school Science
00002   John    High school Math
00003   John    High school *Soccer*
00004   John    High school English
00005   Andrea  High school Math
00006   Andrea  High school Science
00007   Andrea  High school English
00008   Susan   High school History
00009   Susan   High school English
00010   Susan   High school Math
00011   Michael High school Since
00012   Michael High school Math
00013   Michael High school *Basketball*
00014   Michael High school English
00015   Mary    Middle school   Math

我试过这样使用 'EXISTS'：

SELECT ID, name, level FROM Students WHERE level = 'High school' AN NOT EXISTS(
   SELECT * FROM Students WHERE subject IN ('Soccer', 'Basketball') );

结果应该是：

Andrea  High school
Susan   High school

Answer 1

您需要使用 name 列 将您的子查询与外部查询相关联 :

SELECT DISTINCT s.name,  s.level
FROM students s
WHERE s.level = 'High school'
AND NOT EXISTS (
    SELECT 1 FROM students s1 WHERE s1.name = s.name AND s1.subject IN ('Soccer', 'Basketball')  
)

没有相关性，子查询实际上检查 students 中的所有记录是否具有与 'Soccer' 和 'Basketball' 不同的主题，即false，导致外部查询没有返回任何结果。

这个 demo on Db Fiddle 与您的样本数据产量：

| name   | level       |
| ------ | ----------- |
| Andrea | High school |
| Susan  | High school |

Answer 2

请试试这个。

SELECT DISTINCT ID, name, level FROM Students WHERE level = 'High school' AND  subject NOT IN ('Soccer', 'Basketball') ;

MySQL - Select 所有不包含特定值的唯一记录

MySQL - Select all unique records that do not contain certain values

sql

select

exists

distinct