MySQL触发器：根据提交的值更新列

Question

Ths my trigger but it doesn't work.

CREATE TRIGGER events_events_a BEFORE INSERT ON events_events
FOR EACH ROW
BEGIN 
IF NEW.public = 1 THEN
UPDATE events_cats SET etotal=etotal+1, etotal_NEW.region=etotal_NEW.region+1 WHERE id=NEW.category;
END IF;
END;

I need to update column depending of a submitted value.

if NEW.region value is 1, I need to update column etotal_1=etotal_1+1
if NEW.region value is 2, I need to update column etotal_2=etotal_2+1
if NEW.region value is 3, I need to update column etotal_3=etotal_3+1

etc. Is there any way how to update column depending of NEW.region value?

Answer 1

You cannot create a new column name. This is as true for update as for other SQL statements. You can explicitly list the columns for the update:

UPDATE events_cats
    SET etotal = etotal + 1,
        etotal_1 = (case when new.region = 1 then etotal_1 + 1 else etotal_1 end),
        etotal_2 = (case when new.region = 2 then etotal_2 + 1 else etotal_1 end),
        etotal_3 = (case when new.region = 3 then etotal_3 + 1 else etotal_1 end)
    WHERE id = NEW.category;