STATS_MODE takes as its argument a set of values and returns the value that occurs with the greatest frequency. If more than one mode exists, then Oracle Database chooses one and returns only that one value.
To obtain multiple modes (if multiple modes exist), you must use a combination of other functions, as shown in the hypothetical query:
SELECT x FROM (SELECT x, COUNT(x) AS cnt1
FROM t GROUP BY x)
WHERE cnt1 =
(SELECT MAX(cnt2) FROM (SELECT COUNT(x) AS cnt2 FROM t GROUP BY x));
The following example returns the mode of salary per department in the hr.employees table:
SELECT department_id, STATS_MODE(salary) FROM employees
GROUP BY department_id
ORDER BY department_id, stats_mode(salary);
DEPARTMENT_ID STATS_MODE(SALARY)
------------- ------------------
10 4400
20 6000
30 2500
40 6500
50 2500
60 4800
70 10000
80 9500
90 17000
100 6900
110 8300
7000
If you need to retrieve all of the modes (in cases with multiple modes), you can do so using a combination of other functions, as shown in the next example:
SELECT commission_pct FROM
(SELECT commission_pct, COUNT(commission_pct) AS cnt1 FROM employees
GROUP BY commission_pct)
WHERE cnt1 =
(SELECT MAX (cnt2) FROM
(SELECT COUNT(commission_pct) AS cnt2
FROM employees GROUP BY commission_pct))
ORDER BY commission_pct;
COMMISSION_PCT
--------------
.2
.3