如何编写sql语句？

Question

SELECT IF(s.`name` != '',s.`name`,w.staffname) as '姓名', SUM(w.money) as '当月工资'
FROM wages w, staff s
WHERE s.id = w.staffid AND
    DATE_FORMAT(w.createtime,'%Y-%m')='2022-07' 
GROUP BY w.staffid

这么写问题很多，应该怎么写？

Answer 1

SELECT s.id,
       IFNULL(s. name, w.staffname) as '姓名',
       SUM(w.money) as '当月工资'
  FROM staff s
  left join wages w
    on w.staffid = s.id
 where month(w.createtime) = month(sysdate)
 GROUP BY s.id, IFNULL(s. name, w.staffname) as '姓名'