MySQL 如何在使用 Group By 时为不匹配的列分配空值

Question

我有以下 MovieTheaterTbl 表:

Name      Location      Date    TicketRevenue  SnackRevenue  BeverageRevenue
AMC       Alpine St.    8/14        100             80             60
Atlas     Main St.      8/19        300             150            100
Atlas     Lincoln Rd.   8/19        50              50             40 

我想将此数据插入名为 SummaryTbl 的表中，该表应显示按电影院名称分组的收入列的总和。如果具有相同名称的行的任何其他列不相同(例如，2 个 Atlas 条目中的位置不同)，我希望在该位置显示空值。这就是我希望 SummaryTbl 的样子:

Name      Location      Date    TicketRevenue  SnackRevenue  BeverageRevenue
AMC       Alpine St.    8/14        100             80             60
Atlas                   8/19        350             200           140

这是我目前使用的代码:

insert into  SummaryTbl (Name,Location,Date,TicketRevenue,SnackRevenue,BeverageRevenue)
select Name,Location,Date,sum(TicketRevenue),sum(SnackRevenue), sum(BeverageRevenue)
from MovieTheaterTbl
group by Name

这可以很好地将数据分组在一起，但是当一个电影院有多个位置时，它不会在 Location 字段中插入 NULL 值。有人可以解释一下如何做到这一点吗？谢谢!

Answer 1

你可以使用 union adn having .. having count(*) > 1 insert null else insert the location

  insert into  SummaryTbl (Name,Location,Date,TicketRevenue,SnackRevenue,BeverageRevenue)
  select Name, NULL,Date,sum(TicketRevenue),sum(SnackRevenue), sum(BeverageRevenue)
  from MovieTheaterTbl
  group by Name
  HAVING COUNT(*) >1
  and count(location) >1
  UNION
  select Name, Location,Date,sum(TicketRevenue),sum(SnackRevenue), sum(BeverageRevenue)
  from MovieTheaterTbl
  group by Name
  HAVING COUNT(*) =1
  AND count(location) = 1