create table tb(A int,B int,C int)
insert into tb select 123,222,23
insert into tb select 223,221,23
insert into tb select 223,256,26
insert into tb select 123,22,27
insert into tb select 123,126,29
insert into tb select 223,225,558
insert into tb select 223,256,25
insert into tb select 123,223,30
go
select a.* from tb a inner join(
select * 
from tb a 
where exists(select 1 from tb where a=a.a and c<>a.c and c-a.c between 1 and 3)
and exists(select 1 from tb where a=a.a and c<>a.c and a.c-c between 1 and 3)
)b on a.a=b.a and abs(a.c-b.c)<=3
/*
A           B           C
----------- ----------- -----------
123         22          27
123         126         29
123         223         30
223         221         23
223         256         26
223         256         25

(6 行受影响)

*/
go
drop table tb

------解决方案--------------------
没赶上

------解决方案--------------------
SQL code
create table tb(A int,B int,C int)
insert into tb select 123,222,23
insert into tb select 223,221,23
insert into tb select 223,256,26
insert into tb select 123,22,27
insert into tb select 123,126,29
insert into tb select 223,225,558
insert into tb select 223,256,25
insert into tb select 123,223,30
go
select a.* from tb a inner join(
select a,c 
from tb t
where exists(select 1 from tb where a=t.a and c<>t.c and c-t.c between 0 and 3 group by a having count(*)=2)
)b on a.a=b.a and a.c-b.c between 0 and 3
/*
A           B           C
----------- ----------- -----------
123         22          27
123         126         29
123         223         30
223         221         23
223         256         26
223         256         25

(6 行受影响)

*/
go
drop table tb