Question

我有简单的mysql表，包含2个字段：

atr_id | atr_val_id
1      | 100
1      | 200
1      | 300
2      | 100
3      | 100
3      | 200
4      | 200

如何选择具有atr_val_id = 100 AND 200的所有atr_ids值，仅此而已？在这个例子中，这只是atr_id = 3。或者例如只有200，这将是atr_id = 4

Answer 1

可能有更简单的方法。这里有一个解决方案，它使用group by，group_contact，distinct，sort和having子句的组合来获取所需的结果

具有atr_val_id = 100 AND 200的所有atr_ids值，仅此而已。这将只返回atr_id = 3

select 
    atr_id 
from 
    tbl_test
group by 
    atr_id
having 
    group_concat(distinct atr_val_id order by atr_val_id asc) = '100,200'

仅200，这将返回atr_id = 4

select 
    atr_id 
from 
    tbl_test
group by 
    atr_id
having 
    group_concat(distinct atr_val_id order by atr_val_id asc) = '200'

Answer 2

另一种方法是使用下面的NOT EXISTS

select atr_id 
from table_name t1 
where atr_val_id in(100,200)
AND NOT EXISTS
(
  select 1
  from table_name t2
  where t2.atr_id = t1.atr_id
  group by t2.atr_id
  having count(t2.atr_val_id) < 2 OR count(t2.atr_val_id) > 2 

)
group by t1.atr_id
;

您可以根据您正在查看的atr_val_id的数量更改计数部分。比如说只有200它将成为

having count(t2.atr_val_id) < 1 OR count(t2.atr_val_id) > 1

随后您还需要更改IN子句。

当字段等于许多值时，从mysql表中选择值

2 个答案: