select * from <table> where to_date(create_date) = to_date('20090506', 'YYYYMMDD')

<Table>.find_by_sql("select * from <table> where to_date(create_date) = to_date('20090506', 'YYYYMMDD')")

select * from <table> where create_date = to_date('20090506', 'YYYYMMDD')

Table.find_by_sql("
  select * from <table>
  where to_char(create_date, 'YYYY-MM-DD') = '2009-05-06'
")