A
a1,b1,c1
a2,b2,c2
a3,b3,c3
 

B
a1,d1,e1
a1,d2,e2
a2,d3,e3
a2,d4,e4

已知d2>d1,d4>d3要得到
a1,d1,e1,c1
a2,d3,e3,c2  

給个sql语句吧

--> 测试数据：[ta]
IF OBJECT_ID('[ta]') IS NOT NULL DROP TABLE [ta]
GO 
CREATE TABLE [ta]([a] VARCHAR(2),[b] VARCHAR(2),[c] VARCHAR(2))
INSERT [ta]
SELECT 'a1','b1','c1' UNION ALL
SELECT 'a2','b2','c2' UNION ALL
SELECT 'a3','b3','c3'

--> 测试数据：[tb]
IF OBJECT_ID('[tb]') IS NOT NULL DROP TABLE [tb]
GO 
CREATE TABLE [tb]([a] VARCHAR(2),[b] VARCHAR(2),[c] VARCHAR(2))
INSERT [tb]
SELECT 'a1','d1','e1' UNION ALL
SELECT 'a1','d2','e2' UNION ALL
SELECT 'a2','d3','e3' UNION ALL
SELECT 'a2','d4','e4'
--------------开始查询--------------------------

SELECT b.*,a.c FROM [tb] b INNER JOIN [ta] a
ON a.a=b.a
AND NOT EXISTS(SELECT 1 FROM [tb] WHERE a=b.a AND b<b.b)
----------------结果----------------------------
/* 
a    b    c    c
---- ---- ---- ----
a1   d1   e1   c1
a2   d3   e3   c2

(2 行受影响)


*/

------解决方案--------------------
SQL code

IF EXISTS (SELECT 1 FROM SYSOBJECTS WHERE name = 'A')
BEGIN
    DROP TABLE A
END
GO
CREATE TABLE A
(
    col1 INT,
    col2 INT,
    col3 INT
)
GO
INSERT INTO A
SELECT 1,1,1 UNION
SELECT 2,2,2 UNION
SELECT 3,3,3
GO
IF EXISTS (SELECT 1 FROM SYSOBJECTS WHERE name = 'B')
BEGIN
    DROP TABLE B
END
GO
CREATE TABLE B
(
    col1 INT,
    col2 INT,
    col3 INT
)
GO
INSERT INTO B
SELECT 1,1,1 UNION
SELECT 1,2,2 UNION 
SELECT 2,1,1 UNION
SELECT 2,2,2
GO

SELECT A.col1,B.col2,B.col3,A.col3
FROM B,A
WHERE B.col2 <= ALL(SELECT col2 FROM B AS C WHERE B.col1 = C.col1) AND A.col1 = B.col1

------解决方案--------------------
SQL code

--> 测试数据：[A1]
if object_id('[A1]') is not null drop table [A1]
create table [A1]([cola] varchar(2),[colb] varchar(2),[colc] varchar(2))
insert [A1]
select 'a1','b1','c1' union all
select 'a2','b2','c2' union all
select 'a3','b3','c3'
--> 测试数据：[B2]
if object_id('[B2]') is not null drop table [B2]
create table [B2]([cola] varchar(2),[colb] varchar(2),[colc] varchar(2))
insert [B2]
select 'a1','d1','e1' union all
select 'a1','d2','e2' union all
select 'a2','d3','e3' union all
select 'a2','d4','e4'

select 
a.cola,b.colb,b.colc,a.colc 
from [A1] a inner join [B2] b
on a.cola=b.cola
where not exists(select 1 from [B2] c 
where b.cola=c.cola and c.colb<b.colb and c.colc<b.colc)

/*
cola    colb    colc    colc
a1    d1    e1    c1
a2    d3    e3    c2
*/