高手请进，比较复杂

2009-03-27 03:00:09 82 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

vb 读取比较复杂的json 用Ｅｘｃｅｌ读取比较复杂的json 数据源在： http://bbs.csdn.net/topics/390485808 Private Sub CommandButton2_Click() '比较复杂的json On Error Resume Next bt = Split("order_id,order_sn,type,extension,seller_i 阅读详情

TABLE1:
ID MC AGE
1 A 5
2 A 7
3 A 8
4 A 5
5 B 1
6 B 3
7 C 4
8 C 3
9 C 3
通过select * from table t where age=(select min(age) from table where MC=t.MC ) 得到下面的结果(得到字段AGE（按MC分组）的最小值的记录)：
ID MC AGE
1 a 5
4 a 5
5 b 1
8 c 3
9 c 3
那要再通过怎么样才能得到下面的结果：（上面的结果集中取ID小的记录）
ID MC AGE
1 A 5
4 B 1
7 C 3

...全文

Java项目开发，业务比较复杂如何减少bug 当Java开发工作涉及复杂业务时，可以采取以下方法来减少bug的数量：1、深入了解业务需求。2、模块化和解耦合。3、使用设计模式。4、做好异常处理。5、不断进行测试。6、代码审查和团队合作。7、清晰的文档和注释。8、监控和日志记录。阅读详情

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dawugui 2009-03-27

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create TABLE tb(ID INT,MC VARCHAR(1),AGE INT)

INSERT tb

SELECT 1,  'A',  5 UNION ALL 

SELECT 2,  'A',  7 UNION ALL 

SELECT 3,  'A',  8 UNION ALL 

SELECT 4,  'A',  5 UNION ALL 

SELECT 5,  'B',  1 UNION ALL 

SELECT 6,  'B',  3 UNION ALL 

SELECT 7,  'C',  4 UNION ALL 

SELECT 8,  'C',  3 UNION ALL 

SELECT 9,  'C',  3



select ID ,MC, AGE from

(

  select *, px = (select count(1) from tb  where mc = t.mc and (age < t.age or (age=t.age and id < t.id))) + 1 from tb t

) m

where px = 1

order by mc



drop table tb



/*

ID          MC   AGE         

----------- ---- ----------- 

1           A    5

5           B    1

8           C    3



（所影响的行数为 3 行）

*/

dawugui 2009-03-27

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select ID ,MC, AGE from

(

  select *, px = (select count(1) from tb  where mc = t.mc and (age < t.age or (age=t.age and id < t.id))) + 1 from tb t

) m

where px = 1

order by mc

sdhdy 2009-03-27

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select * from table1 a where not exists(select 1 from table1 where  MC=a.MC and id<a.id)

playwarcraft 2009-03-27

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Create table  T (ID INT,MC VARCHAR(1),AGE INT)

INSERT T

SELECT 1,  'A',  5 UNION ALL 

SELECT 2,  'A',  7 UNION ALL 

SELECT 3,  'A',  8 UNION ALL 

SELECT 4,  'A',  5 UNION ALL 

SELECT 5,  'B',  1 UNION ALL 

SELECT 6,  'B',  3 UNION ALL 

SELECT 7,  'C',  4 UNION ALL 

SELECT 8,  'C',  3 UNION ALL 

SELECT 9,  'C',  3

Go

select min(A.id) as ID,A.mc,A.age 

from T A 

inner join 

( 

select mc,min(age) as age 

from t 

group by mc 

) B 

on A.mc=B.mc and A.age=B.age 

group by A.mc,A.age

/*

id     mc      age

-----------------------

1	A	5

5	B	1

8	C	3



*/

GO

drop table T

playwarcraft 2009-03-27

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select min(A.id) as ID,A.mc,A.age
from T A
inner join
(
select mc,min(age) as age
from t
group by mc
) B
on A.mc=B.mc and A.age=B.age
group by A.mc,A.age

csdyyr 2009-03-27

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DECLARE @TB TABLE(ID INT,MC VARCHAR(1),AGE INT)

INSERT @TB

SELECT 1,  'A',  5 UNION ALL 

SELECT 2,  'A',  7 UNION ALL 

SELECT 3,  'A',  8 UNION ALL 

SELECT 4,  'A',  5 UNION ALL 

SELECT 5,  'B',  1 UNION ALL 

SELECT 6,  'B',  3 UNION ALL 

SELECT 7,  'C',  4 UNION ALL 

SELECT 8,  'C',  3 UNION ALL 

SELECT 9,  'C',  3





SELECT * FROM @TB AS A  WHERE NOT EXISTS(SELECT 1 FROM @TB WHERE MC=A.MC AND ID<A.ID)

/*

ID          MC   AGE         

----------- ---- ----------- 

1           A    5

5           B    1

7           C    4

*/

高手请进，比较复杂

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