Question

（很抱歉，如果之前提出过问题或过于简单）

从表中选择所有唯一的名称，这些学生的等级=“高中”且没有运动（“足球”，“篮球”）科目。

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

我尝试这样使用'EXISTS'：

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

结果应为：

Andrea  High school
Susan   High school

Answer 1

您需要使用name列将子查询与外部查询进行关联：

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 all 条记录是否具有与'Soccer'和'Basketball'不同的主题，这是错误的，导致没有结果由外部查询返回。

此 demo on Db Fiddle 和您的示例数据可得出：

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

Answer 2

请尝试这个。

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

MySQL-选择不包含某些值的所有唯一记录

2 个答案: