>thank you
>
> when i run the code as IS NULL i get error message
>Field "EmpNo" does not accept null values
>
Ok, change it to

insert into emplo  (empno, Tel) ;
select t1.empno, t1.Tel from tel t1 ;
LEFT JOIN emplo T2 on T1.empno = T2.empno where T2.empno IS NULL

You need to use T1.EmpNo, not T2.EmpNo

Alternatively

select Tel.EmpNo, Tel.Tel from Tel ;
where not exists (select 1 from EmpNo where EmpNo = Tel.EmpNo) into cursor curAppend nofilter

insert into Emplo (EmpNo, Tel) select * from curAppend