Db2 11.1

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create table table1 (id int, name varchar(10));
insert into table1 (id, name) values (348, 'Mike');
insert into table1 (id, name) values (349, 'John');
create table table2 (name varchar(10));
insert into table2 (name) values ('Conny');
insert into table2 (name) values ('Fred');
insert into table2 (name) values ('Bond');
insert into table2 (name) values ('Fred');
insert into table1 (id, name)
select
  row_number() over(order by name) + (select max(id) from table1),
  name
from (
  select distinct name as name
  from table2 x
  where not exists (
    select name from table1 y where y.name = x.name
  )
) x;
select * from table1;


ID
NAME


348
Mike

349
John

350
Bond

351
Conny

352
Fred