Oracle 11g Release 2

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ALTER SESSION SET NLS_DATE_FORMAT = 'yy-mm-dd';
CREATE TABLE table_name (registration_date) AS
SELECT SYSDATE FROM DUAL UNION ALL
SELECT DATE '2024-04-01' FROM DUAL UNION ALL
SELECT DATE '1901-04-24' FROM DUAL;
3 rows affected

SELECT ROUND(MONTHS_BETWEEN(sysdate, TO_DATE(c.registration_date, 'dd.mm.yy')) / 12, 1)
        AS Years_Client,
       ROUND(MONTHS_BETWEEN(sysdate, c.registration_date) / 12, 1)
        AS actual_Years_Client
FROM   table_name c


YEARS_CLIENT
ACTUAL_YEARS_CLIENT


4
0

23
.1

.1
123