database - SQL query for finding percentage of new records in a table -

i have 2 tables table1 , table2.

each of these tables have columns column1, column2.

i need find percentage of new column1 in table1 group column2.

1) count of new records in column1 = count of (distinct column1 present in table1 , not in table2).

2) count of distinct column1 in tableone

percentage = (1 / 2) * 100.

what tried is

 select count(distinct column1)      tableone left outer join tabletwo on                      (tableone.column1=tabletwo.column2)      tabletwo.column1 null. 

and this:

select count(distinct column1) tableone. 

now how combine both in single query , group column2.

quick way is:

select ((counta/countb)*100) percentage (          select count(distinct column1) counta,                  (select count(distinct column1) tableone) countb             tableone left outer join tabletwo on                              (tableone.column1=tabletwo.column2)              tabletwo.column1 null) x x 

for grouping column2, have add query. need know column2 want group it.

if need cross reference in between tables (1 & 2) it'll bit more complicated.