对查询结果做特殊行列转换的sql记录

查询结果做特殊行列转换

Example

id | type
1 | 2
1 | 3
1 | 2
2 | 1
2 | 2
2 | 3

Output

id || type1 || type2 || type3 || type4
1 || 0 || 1 || 1 || 1
2 || 1 || 1 || 1 || 0

Resolution

select t.id, sum(t.a), sum(t.b), sum(t.c), sum(t.d)

  from (select t.id,
               t.type,
               case
                 when t.type = 1 then
                  1
                 else
                  0
               end as a,
               case
                 when t.type = 2 then
                  1
                 else
                  0
               end as b,
               case
                 when t.type = 3 then
                  1
                 else
                  0
               end as c,
               case
                 when t.type = 4 then
                  1
                 else
                  0
               end as d
          from t_test t
         group by t.id, t.type) t
 group by t.id

ps：项目中遇到的一种场景，为了方便渲染，需要将值做行列转换，并加上相应的计算，记录于此