触发时创建计划事件的触发器 - Mysql

Question

I have a trigger that updates another table, when it is fired, also, I want to create an scheduled event which is set at the TIME that is SELECTED from the table Assignment using the foreign key relation.

Tables looks like that:

ClassAssignment (Bridge table between Class and Assignment):

classID,
assignmentID

Assignment:

id
deadline DATETIME

CREATE TRIGGER newClassAssignment AFTER INSERT ON classassignment FOR EACH ROW
Begin 
INSERT INTO StudentAssignmentSolution(studentID, assignmentID) 
SELECT s.ID, NEW.assignmentID
FROM Student s
WHERE s.classID = NEW.classID;
CREATE EVENT deadlineMissed
ON SCHEDULE (select deadline from assignment where id = new.assignmentID) 
DO
update StudentAssignmentSolution set solutionDate = CURDATE() assignmentId = new.assignmentID;
END

Hope it makes sense. Thank you =)

Answer 1

No, it's impossible in this form. The event 'schedule' parameter is literal, you can't use a subquery in it. And you can't use the output generated by this subquery - the trigger can't contain dynamic SQL.

The solution:

• You create some service table.
• When your trigger is fired, it inserts the data necessary to create the event into this table.
• You create a basic event procedure that is scheduled often enough. This procedure takes data from the service table and, using dynamic SQL, creates the necessary event procedure.