MySQL 如何在使用分组依据时将空值分配给不匹配的列

Question

我有以下 MovieTheaterTbl table:

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

我想将此数据插入到名为 SummaryTbl 的 table 中，它应该显示 Revenue 列的总和，按电影院名称分组。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

这很好地将数据分组在一起，但当单个电影院有多个位置时，它不会在“位置”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

您可以使用 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

Answer 2

试试这个：

insert into  SummaryTbl (Name,Location,Date,TicketRevenue,SnackRevenue,BeverageRevenue)
select Name, if(count(distinct Location)=1, Location, NULL), Date,sum(TicketRevenue),sum(SnackRevenue), sum(BeverageRevenue)
from MovieTheaterTbl
group by Name

MySQL 如何在使用分组依据时将空值分配给不匹配的列

MySQL How to assign a null value to non matching columns when using Group By

mysql

sql

null

group-by

insert-into