CREATE TABLE paperkeyphrase (paperid NUMBER, keyphraseid NUMBER)
CREATE TABLE cite (citingpaperid NUMBER, citedpaperid NUMBER)
CREATE TABLE author (authorid NUMBER, authorname VARCHAR2)
CREATE TABLE field (fieldid NUMBER)
CREATE TABLE dataset (datasetid NUMBER, datasetname VARCHAR2)
CREATE TABLE journal (journalid NUMBER, journalname VARCHAR2)
CREATE TABLE keyphrase (keyphraseid NUMBER, keyphrasename VARCHAR2)
CREATE TABLE writes (paperid NUMBER, authorid NUMBER)
CREATE TABLE paperdataset (paperid NUMBER, datasetid NUMBER)
CREATE TABLE paperfield (fieldid NUMBER, paperid NUMBER)
CREATE TABLE paper (paperid NUMBER, title VARCHAR2, venueid NUMBER, year NUMBER, numciting NUMBER, numcitedby NUMBER, journalid NUMBER)
CREATE TABLE venue (venueid NUMBER, venuename VARCHAR2)

papers before 2010 about character recognition
SELECT DISTINCT paper.paperid FROM keyphrase, paper, paperkeyphrase WHERE keyphrase.keyphrasename = 'character recognition' AND paperkeyphrase.keyphraseid = keyphrase.keyphraseid AND paper.paperid = paperkeyphrase.paperid AND paper.year < 2010
SELECT DISTINCT "paper"."paperid" FROM "keyphrase" JOIN "paperkeyphrase" ON "keyphrase"."keyphraseid" = "paperkeyphrase"."keyphraseid" JOIN "paper" ON "paper"."paperid" = "paperkeyphrase"."paperid" AND "paper"."year" < 2010 WHERE "keyphrase"."keyphrasename" = 'character recognition'