具有特定条件的 MySQL GROUP BY

如何解决具有特定条件的 MySQL GROUP BY

我正在使用 MySQL 5.5。这是我的查询，第一部分显示有关公司及其车辆的信息，第二部分仅显示公司信息。

我做了 UNION 部分，因为一些小客户没有任何车辆，而且由于在第一部分 join 有车辆，那些没有出现。

有什么问题，第一部分和第二部分的一些寄存器有相同的小客户端，而且由于在车辆部分我已经显示了公司信息，我想分组，只有当它们是相同的 idClient 和相同的部门，并且 numberPlate 不为 null（如果它为 null 没关系，我只想删除那些已经在车辆部分显示的冗余原因信息的寄存器）。

有些公司也可以有多个车牌，而且不能分组，因为每个车牌都有自己的文档（这个查询比真实的要小）。

现在的结果：

idClient  company          department    numberplate
3345      TONY FERGUSON    Commercial    null
3345      TONY FERGUSON    Financial     null
3345      TONY FERGUSON    Commercial    8453JVD

在这个例子中，第一个寄存器应该没有了，因为这个客户端有一个号码板，并且同部门（第一个）的寄存器是多余的，因为第三个寄存器显示相同。

另一个例子：

idClient  company          department               numberplate
1267      TERRY SL         Distribution - France    null
1267      TERRY SL         Distribución - France    6381JHZ
1267      TERRY SL         Forwarding UK            null
1267      TERRY SL         Forwarding UK            6381JHZ

在这种情况下，第一个和第三个寄存器应该消失，希望我解释清楚。

这是我的查询：

select  
    idClient as "IdClient",Company  as "Company",if (Department is null,"",Department) as "Department",Numberplate,from      
    (select
         sc.idClient as idclient,sc.businessname as company,d.name as department,v.numberplate as numberPlate,from entity_type et
         join bigClient bc on bc.idClient=et.idClient
         join smallClient sc on sc.idclient=bc.idClientAssociated
         join clientVehicle cv on cv.idClientVehicle=sc.idClientVehicle
         join vehicle v on v.idVehicle=cv.idVehicle    
         join active_vehicle av on av.idEntityType=et.idEntityType and av.idClientVehicle=cv.idClientVehicle 
         left join department d on d.idDepartment=et.idDepartment   
         where bc.idClient=1234   
    UNION
    select 
         c.idClient as idclient,c.businessname as empresavehicle,cd.name as departament,null as matricula,from entity_type et
         join bigClient bc on bc.idClient=et.idClient
         join smallClient sc on sc.idclient=bc.idClientAssociated
         join active_c ac on ac.idEntityType=et.idEntityType and ac.idBigClient=bc.idBigClient   
         left join department d on d.idDepartment=et.idDepartment        
         where bc.idClient=1234) t
    order by company,numberplate;

解决方法

您可以使用解析函数 count 如下：

select * from
(select  
    idClient as "IdClient",Company  as "Company",if (Department is null,"",Department) as "Department",Numberplate,count(Numberplate) over (partition by idClient,company,department) as cnt
  from
    .... rest of your query ....
) t
where cnt = 0 or (cnt>0 and Numberplate is not null)

,

@Popeye 解决方案应该适用于 MySQL 8.o 或更高版本，对于 MySQL 5.x 我可以建议下一步：

select  
    idclient as "IdClient",company  as "Company",if (department is null,department) as "Department",group_concat(numberplate) as,from      
    (select
         sc.idClient as idclient,sc.businessname as company,d.name as department,v.numberplate as numberplate,from entity_type et
         join bigClient bc on bc.idClient=et.idClient
         join smallClient sc on sc.idclient=bc.idClientAssociated
         join clientVehicle cv on cv.idClientVehicle=sc.idClientVehicle
         join vehicle v on v.idVehicle=cv.idVehicle    
         join active_vehicle av on av.idEntityType=et.idEntityType and av.idClientVehicle=cv.idClientVehicle 
         left join department d on d.idDepartment=et.idDepartment   
         where bc.idClient=1234   
    UNION
    select 
         c.idClient as idclient,c.businessname as company,cd.name as departament,null as numberplate,from entity_type et
         join bigClient bc on bc.idClient=et.idClient
         join smallClient sc on sc.idclient=bc.idClientAssociated
         join active_c ac on ac.idEntityType=et.idEntityType and ac.idBigClient=bc.idBigClient   
         left join department d on d.idDepartment=et.idDepartment        
         where bc.idClient=1234) t
    group by idClient,Company,Department
    order by company,numberplate;

这个查询应该有一个限制 - 如果不同的车牌它返回一个连接的字符串