Question

我必须关注表格，我想加入它们，其中icd9中的序列为1，每个主题在入学表中都有一个hadm_id。每个主题可以有多个hadm_id，但我想要那些只有1个hadm_id的人。我也想要序列值为1的主题。

icd9
+-------------+--------------+------+-----+---------+-------+
| Field       | Type         | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+-------+
| subject_id  | int(11)      | NO   | MUL | NULL    |       |
| hadm_id     | int(11)      | NO   | MUL | NULL    |       |
| sequence    | int(11)      | NO   |     | NULL    |       |
| code        | varchar(100) | NO   |     | NULL    |       |
| description | varchar(255) | YES  |     | NULL    |       |
+-------------+--------------+------+-----+---------+-------+

admissions 
+------------+----------+------+-----+---------+-------+
| Field      | Type     | Null | Key | Default | Extra |
+------------+----------+------+-----+---------+-------+
| hadm_id    | int(11)  | NO   | PRI | NULL    |       |
| subject_id | int(11)  | NO   | MUL | NULL    |       |
| admit_dt   | datetime | NO   |     | NULL    |       |
| disch_dt   | datetime | NO   |     | NULL    |       |
+------------+----------+------+-----+---------+-------+

我的查询如下。当我运行它时，我得到以下错误

select * from icd9 
  where sequence=1 as t1
inner join 
  (select * from 
    (select subject_id, count(hadm_id) 
      as n_admissions from admissions 
      group by subject_id
    ) as q1 
  where n_admissions = 1 
  order by subject_id limit 10) as q2
AS t2 
ON t1.subject_id = q2.subject_id;

我不确定如何解决此错误。我尝试了几种方法，但我一直都这样做。

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'as t1
inner join 
  (select * from 
    (select subject_id, count(hadm_id) 
    ' at line 2

Answer 1

试试这个：

select * 
from icd9 as t1
inner join 
    (
     select subject_id
     from admissions 
     group by subject_id
     having count(hadm_id) = 1
     order by subject_id 
     limit 10
    ) as q2
ON t1.subject_id = q2.subject_id and t1.sequence = 1;

这样，您正在进行分组，使用HAVING进行过滤，在一个子查询中进行排序和限制，然后加入icd9。

mysql连接两个表以获取特定列为特定值的位置

1 个答案: