如何从内部联接查询之一中获取总数？

Posted 2023-02-24

【中文标题】如何从内部联接查询之一中获取总数？

【英文标题】：How to get total count from one of the inner join queries?

【发布时间】：2020-08-02 11:50:11

【问题描述】：

我写了下面的mysql查询，Mysql版本是8.0.18-commercial

SELECT p.server, 'Type1' AS Check_Type, 
       GROUP_CONCAT(vmtable.res SEPARATOR ', ') AS result
FROM server p 
INNER JOIN truns t ON t.oq_id = p.oq_id
    AND t.id = (SELECT t2.id FROM truns t2 
                WHERE t2.oq_id = p.oq_id 
                order by t2.created_at desc limit 1 )
INNER JOIN qvuln_info vmtable ON vmtable.run_id = t.id 
LEFT JOIN qvuln_info_data vmtableinfo ON vmtableinfo.qid = vmtable.qid   
WHERE p.server regexp 'server1'
GROUP BY p.server

我得到的输出是：

Hostname   Check_Type  result
server1    Type_ABC    Result 1,Result 2,Result 3,Result 4

我想在顶层添加另一列VulCount，该值应该来自一个内部连接查询：

SELECT t2.id 
FROM truns t2 
WHERE t2.oq_id = p.oq_id 
order by t2.created_at desc

输出应如下所示：

Hostname   VulCount    Check_Type  result
server1    4            Type_ABC       Result 1,Result 2,Result 3,Result 4

这里，4 是

的输出

SELECT count(*) 
FROM truns t2 
WHERE t2.oq_id = p.oq_id 
order by t2.created_at desc

【参考方案1】：

@mealhour 你不能像这样包含子查询：

SELECT p.server, 
       der.VulCount,
       'Type1' AS Check_Type, 
       GROUP_CONCAT(vmtable.res SEPARATOR ', ') AS result
FROM server p 
INNER JOIN truns t ON t.oq_id = p.oq_id
    AND t.id = (SELECT t2.id FROM truns t2 
                WHERE t2.oq_id = p.oq_id 
                order by t2.created_at desc limit 1 )
INNER JOIN qvuln_info vmtable ON vmtable.run_id = t.id 
LEFT JOIN qvuln_info_data vmtableinfo ON vmtableinfo.qid = vmtable.qid 
JOIN (SELECT t2.oq_id, 
          count(t2.*) as VulCount
      FROM truns t2 
      GROUP BY t2.oq_id) AS der  
WHERE p.server regexp 'server1'
    AND der.oq_id = p.oq_id
GROUP BY p.server

【讨论】：

我收到一个错误Error Code: 1064. 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 VulCount FROM truns t2 GROUP BY t2.oq_id) AS d' at line 53 0.078 sec

@mealhour 将t2.* 更改为每行唯一的值以获取计数，最常见的是id 列。如果您有一个独特的列，例如 id 将 count(t2.*) 更改为 count(t2.id)，那应该为您完成