Sqlserver
 sql >> Database >  >> RDS >> Sqlserver

Come calcolare la percentuale con un'istruzione SQL

  1. Il più efficiente (usando over()).

    select Grade, count(*) * 100.0 / sum(count(*)) over()
from MyTable
group by Grade

  2. Universale (qualsiasi versione SQL).

    select Grade, count(*) * 100.0 / (select count(*) from MyTable)
from MyTable
group by Grade;

  3. Con CTE, il meno efficiente.

    with t(Grade, GradeCount) 
as 
( 
    select Grade, count(*) 
    from MyTable
    group by Grade
)
select Grade, GradeCount * 100.0/(select sum(GradeCount) from t)
from t;