このようなMySQLテーブルのピボットとカウント方法は？

Question

私は以下の表を持っています。どのように私はそれをピボットし、各質問の回答を数えることができますか？ 2番目のテーブルは私の望む結果です。

Answer 1

これを試してみてください、あなたはあなたのテーブル名に@tableを交換する必要があります。

select 
    'Q1' as Question, 
    sum(if(Q1='yes', num, 0)) as 'yes', 
    sum(if(Q1='no', num, 0)) as 'no', 
    sum(if(Q1='could be', num, 0)) as 'could be' 
from (select Q1, count(Q1) as num from @table group by Q1) Q1 
union 
select 
    'Q2' as Question, 
    sum(if(Q2='yes', num, 0)) as 'yes', 
    sum(if(Q2='no', num, 0)) as 'no', 
    sum(if(Q2='could be', num, 0)) as 'could be' 
from (select Q2, count(Q2) as num from @table group by Q2) Q2 
union 
select 
    'Q3' as Question, 
    sum(if(Q3='yes', num, 0)) as 'yes', 
    sum(if(Q3='no', num, 0)) as 'no', 
    sum(if(Q3='could be', num, 0)) as 'could be' 
from (select Q3, count(Q3) as num from @table group by Q3) Q3 
union 
select 
    'Q4' as Question, 
    sum(if(Q4='yes', num, 0)) as 'yes', 
    sum(if(Q4='no', num, 0)) as 'no', 
    sum(if(Q4='could be', num, 0)) as 'could be' 
from (select Q4, count(Q4) as num from @table group by Q4) Q4