Database: imdb_minus_1_0
Question: Which producer has worked with the most number of directors ?
SQL: select t4.name from director_directed_by as t1 join movie as t2 on t1.msid = t2.mid join made_by as t3 on t2.mid = t3.msid join producer as t4 on t3.pid = t4.pid group by t4.name order by count ( distinct t1.name ) desc limit 1 ;