Question

这是我为postgresql编写的代码类型的一个非常具体的问题，我正在迁移到mysql以满足项目需求。

到目前为止在mysql中编写的代码如下：

(select substring(dt,1,9) as dt,concat(vish,visl,visn) as vis,ip
    from assignment_walmart.b 
    where service='ss' and ua not like '%ktxn%' 
        and ua not like '%khte%' 
        and ua not like '%keynote%' 
        group by 1,2,3
    ) as A1

    left join // This is where it shows the error.

    (select ip,flag from 
    assignment_walmart.b1 
    group by 1,2    
    ) as A2

    on A1.ip=A2.ip
    where A2.flag is NULL
    group by 1,2;

错误在两个选定表的命名附近弹出“A1”和“A2”，所以我假设在mysql中不允许这样做。

请您帮我解决上述代码的替代语法，因为我必须以这种方式使用这两个表才能加入以获得所需的结果。

我究竟如何使用别名或以明显在postgresql中工作的方式连接2个表？

任何帮助都将不胜感激。

Answer 1

您有一个子查询加入另一个查询。这在任一数据库中都不起作用。您需要将它们包含在select或类似的内容中：

select A2.dt, A2.vis, count(*)
from (select substring(dt,1,9) as dt, concat(vish,visl,visn) as vis,ip
      from assignment_walmart.b 
      where service='ss' and ua not like '%ktxn%' 
          and ua not like '%khte%' 
          and ua not like '%keynote%' 
      group by substring(dt,1,9), concat(vish,visl,visn), ip
     ) as A1 left join // This is where it shows the error.
     (select ip,flag from 
      assignment_walmart.b1 
      group by ip, flag
     ) as A2
     on A1.ip=A2.ip
where A2.flag is NULL
group by A2.dt, A2.vis;

我猜测你想要外部查询的内容以及聚合字段是什么。明确哪些字段正在聚合是个好主意。

Answer 2

看起来你错过了外部查询的SELECT ... FROM。

您认为您的查询的形式为：

SELECT ...
  FROM ( inline view query ) A1
  LEFT
  JOIN ( inline view query ) A2
    ON A1.col = A2.col ...
 WHERE ...
 GROUP BY ...

MySQL错误代码1064语法错误

2 个答案: