SELECT (

CASE WHEN moms_age >17
AND moms_age <25
THEN '18-24'
WHEN moms_age >24
AND moms_age <35
THEN '25-34'
WHEN moms_age >34
AND moms_age <45
THEN '35-44'
WHEN moms_age >44
AND moms_age <55
THEN '45-54'
ELSE 'Other'
END
) AS age_group
FROM users u
JOIN report_dob rdob ON rdob.uid = u.uid
GROUP BY age_group