CUME_DIST is one of the vital Analytic functions of Oracle. It is used to get a cumulative distribution of a value in a group of values. The CUME_DIST function is supported in the various versions of the Oracle/PLSQL, including, Oracle 12c, Oracle 11g, Oracle 10g and Oracle 9i.
CUME_DIST ( expr_1, expr_2, .. expr_n ) WITHIN GROUP ( ORDER BY expr_1, expr_2, .. expr_n )
expr_1, expr_2, .. expr_n:
They are used to specify the expressions to be used for identifying a unique row in the group.
select CUME_DIST(100, 20) WITHIN GROUP (ORDER BY marks, extra) from students;
Here, the cumulative distribution of a student with a total marks of 100 and an extra marks of 20 from within the students table will be returned.