oracle - Retrieving the first value of the column to a variable in pl sql -

i'll try clear possible.

i have these 3 tables customer, link & customer_link.

i using following query retrieve customer_no column customer has values not available in customer_no of table customer_link:

select c.customer_no  customer c  left join customer_link cl         on c.customer_no = cl.customer_no  cl.customer_no null 

the table customer_link has following columns:

id (generated automatically using sequence) customer_no (linked customer table) link_no (linked link table) maker_id  

what i'm trying is, use above query customer_no customer table not added table customer_link yet (this constraint since customer_link cannot have same customer_no twice in table unique. same goes link_no well) & similar query link_no link table.

then use link_no & customer_no respective results & add table customer_link (there function need call values in result).

i need use loop here can update results after adding value each table table customer_link not error trying add same customer_no or link_no twice table.

using cursor 1 way found on internet. it's not clear me.

so i'm trying here result unused customer_no customer & link_no link & insert values in row1 respective columns in table customer_link & loop on update results & values in row1 again add them parameter function call

i think doesn't require loop follow step

1) insert customer_no not in customer_link #temp table

select c.customer_no #temp customer c left join customer_link cl on c.customer_no = cl.customer_no cl.customer_no null  

2)insert customer_no customer_link

insert customer_link(customer_no) select customer_no #temp