Oracle 21c

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CREATE TABLE WMS_UT_ACCOUNTBAL (
    customer_id INTEGER,
    unit_id INTEGER,
    nav INTEGER,
    "date" VARCHAR(10)
);
INSERT INTO WMS_UT_ACCOUNTBAL VALUES (16,1254,10,'2020-05-01');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (17,1253,20,'2020-05-02');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (18,1253,30,'2020-05-03');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (16,1254,20,'2020-05-02');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (16,1254,30,'2020-05-03');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (17,1253,20,'2020-05-02');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (17,1255,30,'2020-05-03');
1 rows affected

INSERT INTO WMS_UT_ACCOUNTBAL VALUES (16,1254,20,'2020-05-04');
1 rows affected

SELECT customer_id, unit_id, nav, "date", AVG(nav) OVER(PARTITION BY customer_id, unit_id ORDER BY "date") AS average_nav
FROM WMS_UT_ACCOUNTBAL ;


CUSTOMER_ID
UNIT_ID
NAV
date
AVERAGE_NAV


16
1254
10
2020-05-01
10

16
1254
20
2020-05-02
15

16
1254
30
2020-05-03
20

16
1254
20
2020-05-04
20

17
1253
20
2020-05-02
20

17
1253
20
2020-05-02
20

17
1255
30
2020-05-03
30

18
1253
30
2020-05-03
30

CUSTOMER_ID	UNIT_ID	NAV	date	AVERAGE_NAV
16	1254	10	2020-05-01	10
16	1254	20	2020-05-02	15
16	1254	30	2020-05-03	20
16	1254	20	2020-05-04	20
17	1253	20	2020-05-02	20
17	1253	20	2020-05-02	20
17	1255	30	2020-05-03	30
18	1253	30	2020-05-03	30