Database: academic
Question: return me the author in the " University of Michigan " in Databases area whose papers have more than 5000 sum citations .
SQL: select t1.name from domain_author as t6 join author as t1 on t6.aid  =  t1.aid join domain as t3 on t3.did  =  t6.did join organization as t5 on t5.oid  =  t1.oid join writes as t2 on t2.aid  =  t1.aid join publication as t4 on t2.pid  =  t4.pid where t3.name  =  "databases" and t5.name  =  "university of michigan" group by t1.name having sum ( t4.citation_num )  >  5000