UPDATE t1
SET t1.avg50 = 1 FROM t2
WHERE t1.ID = (CASE WHEN t2.ID* 5 <= SELECT MAX(ID)FROM t1 THEN t2.ID*5
ELSE SELECT MAX(ID) FROM t1)
SET t1.avg50 = 1 FROM t2
WHERE t1.ID = (CASE WHEN t2.ID* 5 <= SELECT MAX(ID)FROM t1 THEN t2.ID*5
ELSE SELECT MAX(ID) FROM t1)
SET t1.avg50 = 1 FROM t2
WHERE t1.ID = (CASE WHEN t2.ID* 5 <= SELECT MAX(ID) FROM t1 THEN t2.ID*5
ELSE SELECT MAX(ID) FROM t1)
--try
UPDATE t1
SET t1.avg50 = 1
FROM t2
WHERE t1.ID = (CASE WHEN t2.ID* 5 <= (SELECT MAX(ID)FROM t1) THEN t2.ID*5
ELSE (SELECT MAX(ID) FROM t1) end)
update a
set a.avg50 = 1
from t1 a, t2 b
where a.ID = b.ID * 5 or a.ID = (select max(ID) from t1)
UPDATE t1 SET avg50=1 FROM (SELECT MAX(ID) id FROM t1) a,t2 b
WHERE ID =(CASE WHEN b.ID*5<= a.id THEN b.ID*5 ELSE a.id end)