Question

我有两张桌子。一个是：

+--------------------------+-------------+------+-----+---------+
| Field                    | Type        | Null | Key | Default |  
+--------------------------+-------------+---------+-----+------+ 
| facility_id              | int(10)     | NO   | PRI | NULL    |  
| facility_name            | varchar(30) |      |     | NULL    |                 
| facility_model           | varchar(25) |      |     | NULL    |                 
+--------------------------+-------------+------+-----+---------+

另一个是：

+--------------------------+-------------+------+-----+---------+
| Field                    | Type        | Null | Key | Default | 
+--------------------------+-------------+---------+-----+------+ 
| facility_id              | int(10)     | NO   | PRI | NULL    | 
| facility_serial_number   | varchar(30) |      |     | NULL    |                 
+--------------------------+-------------+------+-----+---------+

不同的设施可以具有相同的facility_serial_number（这是我们想要找出并修复的）。我想获得其facility_serial_number不止一次出现的所有设施信息。

我尝试使用group by并拥有：

select f1.facility_id, f1.facility_name, f1.facility_model, f2.facility_serial_number
from f1, f2 on f1.facility_id = f2.facility_id
group by f2.facility_serial_number
having count (facility_serial_number) > 2

这是错的。我也尝试过其他方法，但没有成功。什么是corerct查询语法？

Answer 1

你的内容与你的sql有什么关系并不明显，但是正确的syntac就像是

select  f1.facility_id, 
        f1.facility_name, 
        f1.facility_model, 
        f2.facility_serial_number 
from    f1 INNER JOIN
        f2  on  f1.facility_id = f2.facility_id 
group by    f1.facility_id, 
            f1.facility_name, 
            f1.facility_model, 
            f2.facility_serial_number
having count (facility_serial_number) > 2

或

select  f2.facility_serial_number 
from    f1 INNER JOIN
        f2  on  f1.facility_id = f2.facility_id 
group by    f2.facility_serial_number
having count (facility_serial_number) > 2

但如果我理解正确你可能想尝试类似

的东西

select  f1.facility_id, 
        f1.facility_name, 
        f1.facility_model, 
        f2.facility_serial_number 
from    f1 INNER JOIN
        f2  on  f1.facility_id = f2.facility_id 
WHERE   f2.facility_serial_number IN (
                                        select  f2.facility_serial_number 
                                        from    f1 INNER JOIN
                                                f2  on  f1.facility_id = f2.facility_id 
                                        group by    f2.facility_serial_number
                                        having count (facility_serial_number) > 2
                                    )

Answer 2

尝试关注Ref

SELECT f1.facility_id, f1.facility_name, f1.facility_model, f2.facility_serial_number 
FROM f1 LEFT JOIN f2 on f1.facility_id = f2.facility_id 
GROUP BY f2.facility_serial_number 
HAVING count (f2.facility_serial_number) > 2

Answer 3

select * form f1 from where facility_id in(
select facility_id where f2 group by facility_id
 having count(facility_serial_number) > 2))

SQL Group By和Having error

3 个答案: