create table tb
(id int,
 pathcode varchar(50)
)
insert into tb values(1,'')
insert into tb values(2,'/1')
insert into tb values(3,'/1/2')
insert into tb values(4,'/1/2')
insert into tb values(5,'/1/2')
insert into tb values(6,'/1/2/4')
insert into tb values(7,'7 /1/2/4')
insert into tb values(8,'/1/2/4/5')

 

select max(id)    from tb

 where   len(pathcode) - len(replace(pathcode,'/',''))  =2
 
-----------
5

(1 行受影响)