sql求和问题

有这样一张表
 类型 金额
 a 10
 a 20
 b 10
 a 30
 b 30
我想通过一条sql语句同时查询出a的金额总和和b的金额总和

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SQL code:
select 类型,sum(金额)金额
from tb
group by 类型

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SQL code:
select 类型,SUM(金额) from tb group by 类型

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SQL code:
select
sum(case 类型 when a then 金额 else 0 end) as 'a',
sum(case 类型 when a then 金额 else 0 end) as 'b'
from
tb

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SQL code:
select
sum(case 类型 when a then 金额 else 0 end) as 'a',
sum(case 类型 when b then 金额 else 0 end) as 'b'
from
tb

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引用

SQL code
select
sum(case 类型 when a then 金额 else 0 end) as 'a',
sum(case 类型 when b then 金额 else 0 end) as 'b'
from
tb

姐姐
少引号了

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引用

引用 4 楼 fredrickhu 的回复:
SQL code
select
sum(case 类型 when a then 金额 else 0 end) as 'a'