Oracle9i SQL Reference Release 1 (9.0.1) Part Number A9012501 

Functions, 29 of 166
cume_dist_aggregate::=
cume_dist_aggregate
cume_dist_analytic::=
cume_dist_analytic
CUME_DIST
calculates the cumulative distribution of a value in a group of values. The range of values returned by CUME_DIST
is >0 to <=1. Tie values always evaluate to the same cumulative distribution value.
CUME_DIST
calculates, for a hypothetical row R identified by the arguments of the function and a corresponding sort specification, the relative position of row R among the rows in the aggregation group. Oracle makes this calculation as if the hypothetical row R were inserted into the group of rows to be aggregated over. The arguments of the function identify a single hypothetical row within each aggregate group. Therefore, they must all evaluate to constant expressions within each aggregate group. The constant argument expressions and the expressions in the ORDER
BY
clause of the aggregate match by position. Therefore, the number of arguments must be the same and their types must be compatible.
CUME_DIST
computes the relative position of a specified value in a group of values. For a row R, assuming ascending ordering, the CUME_DIST
of R is the number of rows with values lower than or equal to the value of R, divided by the number of rows being evaluated (the entire query result set or a partition).
The following example calculates the cumulative distribution of a hypothetical employee with a salary of $15,500 and commission rate of 5% among the employees in the sample table oe.employees
:
SELECT CUME_DIST(15500, .05) WITHIN GROUP (ORDER BY salary, commission_pct) "CumeDist of 15500" FROM employees; CumeDist of 15500  .972477064
The following example calculates the salary percentile for each employee in the purchasing area. For example, 40% of clerks have salaries less than or equal to Himuro.
SELECT job_id, last_name, salary, CUME_DIST() OVER (PARTITION BY job_id ORDER BY salary) AS cume_dist FROM employees WHERE job_id LIKE 'PU%'; JOB_ID LAST_NAME SALARY CUME_DIST     PU_CLERK Colmenares 2500 .2 PU_CLERK Himuro 2600 .4 PU_CLERK Tobias 2800 .6 PU_CLERK Baida 2900 .8 PU_CLERK Khoo 3100 1 PU_MAN Raphaely 11000 1

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