-- Database schema
| Author : Id [ INTEGER ] primary_key , Name [ TEXT ] , Affiliation [ TEXT ] | Conference : Id [ INTEGER ] primary_key , ShortName [ TEXT ] , FullName [ TEXT ] , HomePage [ TEXT ] | Journal : Id [ INTEGER ] primary_key , ShortName [ TEXT ] , FullName [ TEXT ] , HomePage [ TEXT ] | Paper : Id [ INTEGER ] primary_key , Title [ TEXT ] , Year [ INTEGER ] , ConferenceId [ INTEGER ] Paper.ConferenceId = Conference.Id , JournalId [ INTEGER ] Paper.JournalId = Journal.Id , Keyword [ TEXT ] | PaperAuthor : PaperId [ INTEGER ] PaperAuthor.PaperId = Paper.Id , AuthorId [ INTEGER ] PaperAuthor.AuthorId = Author.Id , Name [ TEXT ] , Affiliation [ TEXT ] |
-- -- In how many papers and in what years was the International Conference on Database Theory published?

SELECT COUNT(T1.Id) AS PAPER, COUNT(DISTINCT T1.Year) AS YEARS FROM Paper AS T1 INNER JOIN Conference AS T2 ON T1.ConferenceId = T2.Id WHERE year != 0 AND T2.FullName = 'International Conference on Database Theory';