-- 逻辑拆解：条件——Tom，2023年，每个月，消费；求值：金额。按照条件筛选，求值即可
SELECT
    DATE_FORMAT(t2.t_time,'%Y-%m') time,
    SUM(t2.t_amount) total
FROM customer t1
LEFT JOIN trade t2
ON t1.c_id = t2.t_cus
WHERE t1.c_name = 'Tom'
AND YEAR(t2.t_time) = 2023
AND t2.t_type = 1
GROUP BY DATE_FORMAT(t2.t_time,'%Y-%m')
ORDER BY time