SQL запрос

CREATE TABLE #t (d DATE, i INT)
INSERT #t SELECT '12.01.2019', 10
INSERT #t SELECT '16.01.2019', 15
INSERT #t SELECT '18.01.2019', 16
INSERT #t SELECT '20.01.2019', 17
INSERT #t SELECT '23.01.2019', 20
INSERT #t SELECT '25.01.2019', 45
INSERT #t SELECT '08.01.2020', 11
INSERT #t SELECT '09.01.2020', 20
INSERT #t SELECT '11.01.2020', 22
INSERT #t SELECT '20.01.2020', 45
INSERT #t SELECT '21.01.2020', 55
INSERT #t SELECT '22.01.2020', 15
INSERT #t SELECT '31.01.2020', 98
 
SELECT DISTINCT t.i
FROM #t t
LEFT JOIN #t t1 ON t1.i=t.i AND t1.d BETWEEN '01.01.2019' AND '01.02.2019'
LEFT JOIN #t t2 ON t2.i=t.i AND t2.d BETWEEN '01.01.2020' AND '01.02.2020'
WHERE t1.i IS NOT NULL AND t2.i IS NOT NULL

WITH tt AS
(SELECT id_g
 FROM t
 WHERE d > '01.01.2019' AND d < '01.02.2019')
 
SELECT DISTINCT id_g FROM tt
WHERE id_g IN (SELECT id_g FROM t
                  WHERE d > '01.01.2020' AND d < '01.02.2020')

SELECT t.i
FROM (
SELECT * FROM #t t WHERE t.d BETWEEN '01.01.2019' AND '01.02.2019'
UNION
SELECT * FROM #t t WHERE t.d BETWEEN '01.01.2020' AND '01.02.2020'
) t
GROUP BY t.i
HAVING COUNT(*)=2

SELECT t.i
FROM (
SELECT id FROM #t t WHERE t.d BETWEEN '01.01.2019' AND '01.02.2019' GROUP BY id
UNION
SELECT id FROM #t t WHERE t.d BETWEEN '01.01.2020' AND '01.02.2020' GROUP BY id
) t
GROUP BY t.i
HAVING COUNT(*)>1