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

most common topics at ACL 2014
SELECT DISTINCT COUNT(paper.paperid), keyphrase.keyphraseid FROM keyphrase, paper, paperkeyphrase, venue WHERE paperkeyphrase.keyphraseid = keyphrase.keyphraseid AND paper.paperid = paperkeyphrase.paperid AND paper.year = 2014 AND venue.venueid = paper.venueid AND venue.venuename = 'ACL' GROUP BY keyphrase.keyphraseid ORDER BY COUNT(paper.paperid) DESC
SELECT DISTINCT COUNT("paper"."paperid"), "keyphrase"."keyphraseid" FROM "keyphrase" JOIN "paperkeyphrase" ON "keyphrase"."keyphraseid" = "paperkeyphrase"."keyphraseid" JOIN "paper" ON "paper"."paperid" = "paperkeyphrase"."paperid" AND "paper"."year" = 2014 JOIN "venue" ON "paper"."venueid" = "venue"."venueid" AND "venue"."venuename" = 'ACL' GROUP BY "keyphrase"."keyphraseid" ORDER BY COUNT("paper"."paperid") DESC