select a.emp_name emp_name, a.noti_no noti_no, isnull(b.seartb_searchcnt, 0) cnt

from (select emp_name, emp_id, noti_no from tb_employee, tb_notify where noti_no between #start# and #end#) a

left outer join

(select seartb_no, seartb_id, seartb_searchcnt from tb_search where seartb_flag = 1 and seartb_no between #start# and #end#)b

on a.noti_no || a.emp_id = seartb_no || seartb_id

order by emp_name, noti_no

위에서요 ||의 의미가 무엇인지좀 가르쳐 주세요//