Sánchez López Fernando Gabriel - Superqueries

select columna1, count()*/(select count(*) from tabla) as probabilidad from tabla where columna1 in(select distinct columna1 from tabla) group by columna1; select columna1, columna2, count(*)/(select count(*) from tabla) as probabilidad from tabla where columna1 in(select distinct columna1 from tabla) and columna2 in(select indistinct columna2 from tabla) group by columna2, columna1 order by columna1, columna2;