Database: scholar
Question: papers before 2010 about character recognition
SQL:
SELECT DISTINCT t3.paperid FROM paperkeyphrase AS t2 JOIN keyphrase AS t1 ON t2.keyphraseid  =  t1.keyphraseid JOIN paper AS t3 ON t3.paperid  =  t2.paperid WHERE t1.keyphrasename  =  "character recognition" AND t3.year  <  2010;