可以创建一个函数来解决问题。

创建函数

SQL> create or replace function trunc_num(
  2    p1  in number
  3  )
  4  return number
  5  is
  6  insert_num number:=0;
  7  begin
  8    select a.a||'000'||b.b into insert_num from (select substr(p1,1,3) a  from dual ) a,(select substr(p1,4,6) b from dual ) b;
  9    return insert_num;
 10    exception
 11   when no_data_found then
 12   dbms_output.put_line('1111');
 13  end;
 14  /
 
 Function created.

检查函数是否生效

SQL> select trunc_num(123456)  from dual;

TRUNC_NUM(123456)
-----------------
 123000456

创建一个测试表

SQL> create table t1(id number);

Table created.

向表里插入数据

SQL> insert into t1 values(trunc_num(123456));
1 row created.

SQL> commit;
Commit complete.

检查表数据

SQL> select * from t1;
        ID
----------
 123000456