Question

我有一个数据库，里面有一堆分为不同颜色的狗：红色，绿色和黄色。

Name    Color
---------------
Dog1    Green
Dog2    Green
Dog3    Yellow
Dog4    Yellow
Dog5    Red
Dog6    Red
etc.

假设我有一张100只狗的桌子，然后我想让它们分成不同的热量，每次加热时有4只狗。问题是红色和绿色的狗不应该在相同的热量下存在。

我已尝试使用MongoDB和SQL数据库，但我无法弄清楚这是否可行。

在SQL中我试过：

SELECT * FROM Dogs 
WHERE color IN ('green', 'yellow') OR color IN ('red', 'yellow')
ORDER BY RAND() LIMIT 4;

但是红色和绿色仍然可以一起选择。任何人都有一些提示如何使这成为可能吗？

Answer 1

假设您的原始表名为#temp：

    declare @holding table (name varchar(max), color varchar(max), heat int)
     declare @name varchar(max)
     declare @color varchar(max)
     declare @heat1 int
     declare @heat2 int
     declare @heat3 int
     declare @heat4 int
     declare @iterator int =1 
     while @iterator<=(Select  max(cast(replace(name,'dog','') as int))  from #temp)
     begin
     select @color= color, @name=name from #temp where name='dog'+cast(@iterator as varchar(max))
     select @heat1=count(*) from @holding where heat=1
     select @heat2=count(*) from @holding where heat=2
     select @heat3=count(*) from @holding where heat=3
     select @heat4=count(*) from @holding where heat=4

     if @color = 'red'
     begin
         if @heat1>=@heat2
         insert @holding 
         select @name, @color, 2
         else 
         insert @holding 
         select @name, @color, 1
     end

     if @color = 'yellow'
     begin
         if @heat1<=@heat2 and @heat1<=@heat3 and @heat1<=@heat4
         insert @holding 
         select @name, @color, 1
         else if @heat2<=@heat1 and @heat2<=@heat3 and @heat2<=@heat4
         insert @holding 
         select @name, @color, 2
         else if @heat3<=@heat1 and @heat3<=@heat2 and @heat3<=@heat4
         insert @holding 
         select @name, @color, 3
         else
         insert @holding 
         select @name, @color, 4
     end

     if @color = 'green'
     begin

         if @heat3>=@heat4
         insert @holding 
         select @name, @color, 4
         else 
         insert @holding 
         select @name, @color, 3

     end

     set @iterator=@iterator+1
     end 

     select * from @holding 
     order by heat, color

Answer 2

这听起来很傻，但你不能按颜色订购吗？你的热量会像所有绿色，全黄色等一样无聊，但它会解决你的问题。

也许像

SELECT * FROM (
    SELECT *, CASE WHEN Color = 'Green' THEN 1 ELSE CASE WHEN Color = 'Yellow' THEN 2 ELSE 3 END END AS o FROM dogs 
) x ORDER BY x.o

选择多个位于同一列的位置

2 个答案: