模糊匹配sql语句

1.模糊匹配，b表记录不在a表中的

select b.name,a.zymc from a
left join b
on instr(b.name,a.zymc) >0
where b.name is null；

2.根据主副id拼出目录

select c.id_directory_parent,
-- c表副id
c.id_directory, -- c表主id
b.id_directory, -- b表主id
a.id_directory, -- a表主id
case when b.id_directory_parent is null then '/' || a.directory_name
when c.id_directory_parent is null then '/' || b.directory_name || '/' ||a.directory_name
else '/' || c.directory_name || '/' || b.directory_name
|| '/' || a.directory_name
end as ml
from r_directory a
left join r_directory b
on a.id_directory_parent = b.id_directory
left join r_directory
c
on b.id_directory_parent
= c.id_directory