题解 | 获取指定客户每月的消费额

SELECT
  DATE_FORMAT(t.t_time,'%Y-%m') AS time,
  ROUND(SUM(IF(t.t_type = 1,t.t_amount,0)),1) AS total  
  FROM trade t LEFT JOIN customer c
  ON t.t_cus = c.c_id
  WHERE c.c_name = 'TOM'
  AND YEAR(t.t_time) = 2023
  GROUP BY  DATE_FORMAT(t.t_time,'%Y-%m')
  ORDER BY  DATE_FORMAT(t.t_time,'%Y-%m');