sqlÇóºÍÎÊÌâ

ÓÐÕâÑùÒ»Õűí
 ÀàÐÍ ½ð¶î
 a 10
 a 20
 b 10
 a 30
 b 30
ÎÒÏëͨ¹ýÒ»ÌõsqlÓï¾äͬʱ²éѯ³öaµÄ½ð¶î×ܺͺÍbµÄ½ð¶î×ܺÍ

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SQL code:
select ÀàÐÍ,sum(½ð¶î)½ð¶î
from tb
group by ÀàÐÍ

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SQL code:
select ÀàÐÍ,SUM(½ð¶î) from tb group by ÀàÐÍ

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SQL code:
select
sum(case ÀàÐÍ when a then ½ð¶î else 0 end) as 'a',
sum(case ÀàÐÍ when a then ½ð¶î else 0 end) as 'b'
from
tb

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SQL code:
select
sum(case ÀàÐÍ when a then ½ð¶î else 0 end) as 'a',
sum(case ÀàÐÍ when b then ½ð¶î else 0 end) as 'b'
from
tb

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ÒýÓÃ

SQL code
select
sum(case ÀàÐÍ when a then ½ð¶î else 0 end) as 'a',
sum(case ÀàÐÍ when b then ½ð¶î else 0 end) as 'b'
from
tb

½ã½ã
ÉÙÒýºÅÁË

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ÒýÓÃ

ÒýÓà 4 Â¥ fredrickhu µÄ»Ø¸´:
SQL code
select
sum(case ÀàÐÍ when a then ½ð¶î else 0 end) as 'a'