在ORACLE中将SQL查询从宽格式转换为长格式

Question

我有这样的SQL查询

select
 group, 
sum(case when field1 = 'a' then 1 else 0 end ) as typea,
sum(case when field1 = 'b' then 1 else 0 end ) as typeb
from mytable
group by group

结果就像

group  typea    typeb
 1      10         30
 2      20          40

效果很好，但我需要这样的结果：

group  types     value
1       typea     10
2       typea      30
1       typeb      20
2       typeb      40

有没有办法修改此查询：

select
 group, 
sum(case when field1 = 'a' then 1 else 0 end ) as typea,
sum(case when field1 = 'b' then 1 else 0 end ) as typeb
from mytable
group by group

这样它将返回我需要的结果？

注意-正在使用ORACLE

谢谢。

Answer 1

使用UNION ALL ：

select "group", 
      'typea' AS type,
       sum(1) AS value
from mytable
where field1 = 'a'
group by "group"
UNION ALL
select "group", 
       'typeb',
       sum(1)
from mytable
where field1 = 'b'
group by "group"

Answer 2

数据已经正确组织，您只需要进行不同的分组即可。

SELECT "group", 'type'||field1 as Types, sum(1) as value
FROM mytable
GROUP BY "group", 'type'||field1
ORDER BY Types, "group"

注释组是一个保留字，因此如果可以将其列和类型重命名，则将其放在“”中，长期来看会更好，因为一个是保留字，另一个是关键字。

With MyTable("group",field1) as  (select 1, 'a' from dual UNION ALL
select 1 , 'a' as field1 from dual UNION ALL
select 1 , 'b' as field1 from dual UNION ALL
select 1 , 'b' as field1 from dual UNION ALL
select 2 , 'a' as field1 from dual UNION ALL
select 2 , 'a' as field1 from dual UNION ALL
select 2 , 'a' as field1 from dual UNION ALL
select 2 , 'b' as field1 from dual)
SELECT "group", 'type'||field1 as Types, sum(1) as value
FROM mytable
GROUP BY "group", 'type'||field1

尽管为什么需要将“类型”作为字段1的前缀，这很奇怪。 这可能只是一个简单的（无关键性的）计数，并且似乎仅需分组。

SELECT "group", field1 as Types, count(*) as value
FROM mytable
GROUP BY "group", field1
ORDER BY Types, "group"