题解 | #计算25岁以上和以下的用户数量#

SELECT 
    CASE 
        WHEN age IS NULL THEN "25岁以下"
        WHEN age <25 THEN "25岁以下"
        WHEN age >= 25 THEN "25岁及以上"
    END AS age_cut,
    COUNT(*) AS number
FROM user_profile
GROUP BY age_cut;