你试试
select a.tabname,a.owner
from SYSTABLES a
where a.tabid not in (select b.tabid from SYSCONSTRAINTS b where b.constrtype='P')
and a.tabid in (select c.tabid from SYSCONSTRAINTS c where c.constrtype='U')
and a.owner <> 'informix'
and a.tabtype='T';
我没有informix的数据库,所以这个SQL没测试过