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mysql compare columns in same table

开发者 https://www.devze.com 2023-03-22 00:55 出处:网络
I have a table in a mysql db as idfruitnumber_eatenday ---------------------------------- 1apple21 2banana11

I have a table in a mysql db as

id  fruit   number_eaten   day   
----------------------------------
1  apple        2           1
2  banana       1           1
3  orange       3           2
4  apple        1        开发者_如何学Go   2
5  banana       2           3
6  peach        1           3

I'm trying to figure out how to select such that I can compare how many was eaten per day and place into a spreadsheet so i get

fruit     number_eaten_day_1   number_eaten_day_2    number_eaten_day_3
------------------------------------------------------------------------
apple             2                  1                      0
banana            1                  0                      2
orange            0                  3                      0
peach             0                  0                      1


it's easier to have separate row per fruit and day with summed value number_eaten:

select fruit, day, sum(number_eaten)
from fruits_eaten_by_day 
group by fruit, day

but it should also be possible to have exact result you need by doing this:

select 
  fruit, 
  sum(if(day=1, number_eaten, 0)) as number_eaten_day_1, 
  sum(if(day=2, number_eaten, 0)) as number_eaten_day_2, 
  sum(if(day=3, number_eaten, 0)) as number_eaten_day_3
from fruits_eaten_by_day
group by fruit
0

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