to_char+fm

select to_char(7630.376,'fm9999000.00999') from dual --7630.376  ok
union all
select to_char( 0.376   ,'fm9999000.00999') from dual --000.376
union all
select to_char(30.376   ,'fm9999000.00999') from dual --030.376
union all
select to_char(30.376   ,'fm9999990.00999') from dual --30.376   ok
union all
select to_char(30.376   ,'fm9999990.09999') from dual --30.376   ok
union all
select to_char(30.376   ,'fm9999990.09')    from dual --30.38  
union all
select to_char(30.376   ,'fm9999990.00')    from dual --30.38    ok 保留2位小数
union all
select to_char(30.3     ,'fm9999990.00999') from dual --30.30
union all
select to_char(30.3     ,'      fm0.00999') from dual --########
;