return me the number of keywords in Databases area .
SELECT COUNT ( DISTINCT t1.keyword ) FROM DOMAIN AS t3 JOIN domain_keyword AS t2 ON t3.did  =  t2.did JOIN keyword AS t1 ON t1.kid  =  t2.kid WHERE t3.name  =  "Databases";
SELECT COUNT ( DISTINCT t1.keyword ) FROM DOMAIN AS t3 JOIN domain_keyword AS t2 ON t3.did  =  t2.did JOIN keyword AS t1 ON t1.kid  =  t2.kid WHERE t3.name  =  "Databases";
[{'COUNT ( DISTINCT t1.keyword )': 0}]