SQL select 列多次使用不同的条件

Question

我有一个 table 事件，其中包含事件中受伤人数的列和事件中死亡人数的列。事件 table 与参与者 table 相关联，您可以在其中找到一个人的年龄列，还有另一个 table ParticipantTypes，其中包含类型列（男（id = 1），女（ id = 2) 例如）。所以，我想检索受伤的列号，类型为男性的列号被杀死，然后是受伤的列号，类型为女性的列号被杀死，全部按年龄分组。

select    
ip.age as age, 
sum(i.number_injured) as injured,
sum(i.number_killed) as killed
from Incidents i
inner join Participants ip on i.id = ip.incident_id
inner join ParticipantTypes ipt on ip.type_id = ipt.id
where ipt.id = 1
group by ip.age

以下查询有效并仅检索 ParticipantTypes.type = 1 (man)

的结果

我想要它

select    
ip.age as age, 
sum(i.number_injured) as injured where ipt.id = 1,
sum(i.number_killed) as killed where ipt.id = 1, 
sum(i.number_injured) as injured where ipt.id = 2,
sum(i.number_killed) as killed where ipt.id = 2, 
from Incidents i
inner join Participants ip on i.id = ip.incident_id
inner join ParticipantTypes ipt on ip.type_id = ipt.id
group by ip.age

Answer 1

您正在 inner join 和 where.

中过滤掉具有 ipt.id = 1 条件的 woman 条记录

此外，您正在按 age 分组，这不是您想要的，正如我从问题中了解到的那样。所以，你的最终查询应该是。

编辑：根据相关更新的详细信息，以下是查询

select
    ip.age,
    sum(case when ipt.id =1 then i.number_injured else 0 end) as men_injured,
    sum(case when ipt.id =1 then i.number_killed else 0 end) as men_killed,
    sum(case when ipt.id =2 then i.number_injured else 0 end) as women_injured,
    sum(case when ipt.id =2 then i.number_killed else 0 end) as women_killed
from Incidents i
       inner join Participants ip on i.id = ip.incident_id
       inner join ParticipantTypes ipt on ip.type_id = ipt.id
group by ip.age

Answer 2

select    
ip.age as age, 
sum(if(ipt.id=1,i.number_injured,0)) as injured_by_man,
sum(if(ipt.id=1,i.number_killed,0) as killed_by_man,
sum(if(ipt.id=2,i.number_injured,0)) as injured_by_woman,
sum(if(ipt.id=2,i.number_killed,0)) as killed_by_woman

from Incidents i
inner join Participants ip on i.id = ip.incident_id
inner join ParticipantTypes ipt on ip.type_id = ipt.id
group by ip.age

注意：上述代码未经测试。它可能包含小语法错误。

Answer 3

试试这个....

select    
ip.age as age, 
sum(case when ipt.id=1then i.number_injured else 0                
end) as injured_by_man,
sum(case when ipt.id=1then i.number_killed else 0  
end) as killed_by_man,
sum(case when ipt.id=2 then i.number_injured else 0 
end) as injured_by_woman,
sum(case when ipt.id=2 then i.number_killed else 0 
end) as killed_by_woman

from Incidents i
inner join Participants ip on i.id = ip.incident_id
inner join ParticipantTypes ipt on ip.type_id = ipt.id
group by ip.age

Answer 4

select    
    ip.age as age, 
    sum(case when ipt.id=1 then i.number_injured    else 0 end)     as injured_man,
    sum(case when ipt.id=1 then i.number_killed     else 0 end)     as killed_man,
    sum(case when ipt.id=2 then i.number_injured    else 0 end)     as injured_woman,
    sum(case when ipt.id=2 then i.number_killed     else 0 end)     as killed_woman
 from 
    Incidents i
inner join 
    Participants ip on i.id = ip.incident_id
inner join 
    ParticipantTypes ipt on ip.type_id = ipt.id
group by ip.age

示例结果：

age         injured_man killed_man  injured_woman killed_woman 
----------- ----------- ----------- ------------- ------------ 
         30          10           1             3            1 
         31          12           1             1            6 
         32          14           2             4            4

SQL select 列多次使用不同的条件

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