MySQL 更新内连接

Question

I tried to update a column in a specific table which has a parent table. The table is gradings and the column in this table whose value I want to update is sy_id.

The other table school_years has column sy_id and sy_dates which having a value. 2018 -2019, 2019 - 2020....

I want to update the column sy_id in gradings but I have no idea how to solve the error.

UPDATE gradings
INNER JOIN school_years
ON gradings.sy_id = school_years.sy_dates
INNER JOIN students
ON gradings.student_id = students.id
SET gradings.sy_id = '2017 - 2018'
WHERE students.id = 1;

Any thoughts?

Answer 1

Assuming that you are not joining on the wrong columns, this should work fine:

update gradings g,
    school_years sy,
    students s 
set 
    g.sy_id = '2017 - 2018'
where
    g.student_id = s.id
        and g.sy_id = sy.sy_dates
        and s.id = 1