Below is my query:
SELECT
REL_NAME AS Release,
BG_SEVERITY AS Severity,
COUNT (BG_BUG_ID) AS DefectCount
FROM BUG, RELEASES
WHERE BG_DETECTION_DATE BETWEEN to_date ('2014/01/01','yyyy/mm/dd') AND to_date ('2014/12/31','yyyy/mm/dd')
AND BG_DETECTED_IN_REL = REL_ID
GROUP BY REL_NAME,BG_SEVERITY
ORDER BY REL_NAME, BG_SEVERITY