Oracle Control Problem

Question

hi i'm new in oracle and i know that my question might be quite simple but i cannot manage this problem.
here's my question
i have two table (lets say A(name,number,code) and B (task,event) ) and A's number and B's task have same values. what i'm trying to do is if A's number doesn't exist in B's task, then add it to B. (A's number will be B's event)
and A's number might be sth like that 1301-3 1301-5 1302-4 .(their codes are '2') and i have to put them in B like : 1301,1302 (first 4 characters).
i'm trying to do it with a cursor in A's table. cursor fetches on A by records that their code is '2' and their first 4 characters don't match with any record in B's task .
can you help me i can't find a way , i think i have to control first 4 characters in every loop but i couldn't find how to do it .

Answer 1

you have strange column names....
Next time post your tables (CREATE TABLE) and some sample data (INSERT INTO)
NUMBER is a reserved word, don't use it as a column name... especially when it is not a NUMBER :)
Something like this:
SQL> create table a
  2  (numb varchar2(10));
Table created.
SQL>
SQL> insert into a (numb) values ('1301-3');
1 row created.
SQL> insert into a (numb) values ('1301-5');
1 row created.
SQL> insert into a (numb) values ('1302-4');
1 row created.
SQL>
SQL> create table b
  2  (n number);
Table created.
SQL>
SQL> insert into b
  2  select distinct
  3         to_number (substr (numb, 1, instr (numb, '-') -1))
  4    from a
  5  /
2 rows created.
SQL> select *
  2    from b
  3  /
         N
      1302
      1301