Recursive SQL giving ORA-01790

Question

Using Oracle 11g release 2, the following query gives an ORA-01790: expression must have same datatype as corresponding expression:

with intervals(time_interval)         


        

Answer 1

Odd - works if you pass around varchars and convert (not cast):

WITH intervals(time_interval) AS
  (SELECT to_char(TRUNC(systimestamp))
  FROM dual
  UNION ALL
  SELECT to_char(to_timestamp(time_interval) + numtodsinterval(10, 'Minute'))
  FROM intervals
  WHERE to_timestamp(time_interval) < systimestamp
  )
SELECT to_timestamp(time_interval) time_interval
FROM intervals