zOs/SQL/CATDBPR

select min(Name) name, length(strip(Name))
    from sysibm.sysdatabase
    group by length(strip(Name))
    order by 2
 ;
select left(name, 6),  count(*)
    from sysibm.sysdatabase
    group by left(name, 6)
    order by 2 desc
    fetch first 20 rows only