Question

我有表名：目标

id  date        valueweekmodified           goal_type_id    user_id
1   2016-01-07  2   1   2016-01-07 16:21:56 3   3
2   2016-01-07  5   1   2016-01-07 16:21:56 1   3
3   2016-01-07  0   1   2016-01-07 17:17:01 3   4
4   2016-01-07  500 1   2016-01-07 17:17:01 1   4
5   2016-01-07  0   1   2016-01-07 17:50:11 3   6
6   2016-01-07  300 1   2016-01-07 17:50:11 1   6
7   2016-01-07  1   1   2016-01-07 17:52:40 3   5

我想获取那些设置了唯一且唯一一个goal_type_id = 3的用户。

例如：见id 1,2。不应返回该记录，因为user_id = 3有两个goal_type_id = 1和3。

从上表中只有id = 7才有效，因为只有该行包含goal_type_id = 3（对于user_id = 5）。其余的用户设定了两个我不想要的目标。

我该怎么做？

Answer 1

select user_id from goal 
where user_id not in (select user_id from goal where goal_type_id !=3)
and goal_type_id = 3;

整行

select * from goal 
where user_id not in (select user_id from goal where goal_type_id !=3)
and goal_type_id = 3;

或

select id,  date, value, week,modified,   goal_type_id ,user_id
from goal 
where user_id not in (select user_id from goal where goal_type_id !=3)
and goal_type_id = 3;

Answer 2

select user_id
from goal
group by user_id
having bool_and(goal_type_id = 3)

如果所有输入值都为true，则

bool_and返回 true，否则返回false

https://www.postgresql.org/docs/current/static/functions-aggregate.html#FUNCTIONS-AGGREGATE-TABLE

从多个选项中获取数据库中的唯一记录

2 个答案: