mysql - 这条sql语句为什么加上where就报错？

Question

这条SQL

SELECT *,SUM(tuanke_time.time) AS total_time 
FROM `tuanke_time` 
LEFT JOIN tuanke_student ON tuanke_student.Sid = tuanke_time.studentID 
WHERE total_time > 100
GROUP BY tuanke_time.studentID

加上where就报错说不存在total_time列，但是我看了明明存在啊

Answer 1

1. total_time is the alias you get for SUM(tuanke_time.time). The database table field itself does not have this column. total_time 是你给SUM(tuanke_time.time)取得别名，数据库表字段本身没有这列吧。

2. 查询total_time > 100

Query total_time > 100, you can try it🎜🎜 🎜

SELECT *
FROM `tuanke_time` 
LEFT JOIN tuanke_student ON tuanke_student.Sid = tuanke_time.studentID 
GROUP BY tuanke_time.studentID having SUM(tuanke_time.time) > 100;

Answer 2

Total_time is defined in the query output column. This column does not exist in the original table.

Answer 3

On and where in outer joins are equivalent and cannot be repeated. Just remove where