关于分类统计的问题(30分)

P

peterwang

Unregistered / Unconfirmed

GUEST, unregistred user!

• 1999-11-01

• #1

有一个表：
a b
---------
1 100010
2 100011
3 100012
4 100022
5 200011
6 200012

希望用一句select求出 b字段中前4位相同的记录分别有多少。结果要如下：
-----------
4 1000
2 2000

 

A

Another_eYes

Unregistered / Unconfirmed

GUEST, unregistred user!

• 1999-11-01

• #2

local sql:
select count(a), substring(b from 1 for 4) as b from table group by b

 

C

cytown

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GUEST, unregistred user!

• 1999-11-01

• #3

local sql:
select count(*) as cnt_a, substring(b from 1 for 4) as sub_b
from table1
group by substring(b from 1 for 4)

sqlserver:
select count(*) as cnt_a, substring(b, 1, 4) as sub_b
from table1
group by substring(b, 1, 4)

 

J

Jams

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GUEST, unregistred user!

• 1999-11-01

• #4

>>

 

P

pxlei

Unregistered / Unconfirmed

GUEST, unregistred user!

• 1999-11-01

• #5

来晚了.

 

G

guolei

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GUEST, unregistred user!

• 1999-11-01

• #6

来晚了.

 

S

SeaSky

Unregistered / Unconfirmed

GUEST, unregistred user!

• 1999-11-01

• #7

就让让他们吧. ).

 

P

peterwang

Unregistered / Unconfirmed

GUEST, unregistred user!

• 1999-11-02

• #8

多人接受答案了。