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分享select count(distinct a) from b 不可用如何代替。
B表中的A字段有些重复的值，现在要查出A中不重复值有多少个，上面这条SQL说是参数错误，我用的是DBISAM数据库，就是那种DELPHI的第三方控件，有用过的请指点
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ayusay 2003-03-13
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select count(t.*) from (select distinct b.a from b) t
klyh 2003-03-09
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select count(*) from (select distinct a from b)
ZbDerek 2003-03-07
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试一下
select count(*)
from b
group by a having count(*)=1
select count(*)
from b
group by a having count(*)=1
CB123 2002-11-28
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up
walkworm 2002-11-28
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或者：
select count(*) from (select count(A) from B group by A)
select count(*) from (select count(A) from B group by A)
walkworm 2002-11-28
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试试嵌套count：
select count(count(A)) from B group by A
select count(count(A)) from B group by A
