Oracle 18c

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create table product (warranty_period INTERVAL YEAR TO MONTH);
insert into product values(INTERVAL '2-0' YEAR TO MONTH)
1 rows affected

insert into product values(INTERVAL '1-5' YEAR TO MONTH)
1 rows affected

insert into product values(INTERVAL '0-7' YEAR TO MONTH)
1 rows affected

insert into product values(INTERVAL '0-0' YEAR TO MONTH)
1 rows affected

select * from product


WARRANTY_PERIOD


+02-00

+01-05

+00-07

+00-00


SELECT
    WARRANTY_PERIOD,
    CASE
        WHEN WARRANTY_PERIOD > INTERVAL '1-0' YEAR TO MONTH 
        THEN EXTRACT(YEAR FROM WARRANTY_PERIOD)
             || ' years '
             || CASE
                WHEN EXTRACT(MONTH FROM WARRANTY_PERIOD) <> 0 
                THEN EXTRACT(MONTH FROM WARRANTY_PERIOD)
                     || ' month'
                END
        WHEN WARRANTY_PERIOD > INTERVAL '0-1' YEAR TO MONTH 
        THEN EXTRACT(MONTH FROM WARRANTY_PERIOD)
             || ' month'
        ELSE 'No warranty'
    END AS WARRANTY
FROM
    PRODUCT


WARRANTY_PERIOD
WARRANTY


+02-00
2 years

+01-05
1 years 5 month

+00-07
7 month

+00-00
No warranty

WARRANTY_PERIOD	WARRANTY
+02-00	2 years
+01-05	1 years 5 month
+00-07	7 month
+00-00	No warranty