I have a trigger that checks to see if certain fields changed during the update. If any of these fields changed I update another table.
I'd like to "break" out of the if conditions as soon as I know that something changed.
Is there a way to do this within a MySQL Trigger?
What I have works, but It seems inefficient.
CREATE TRIGGER profile_trigger
BEFORE UPDATE ON profile
FOR EACH ROW
BEGIN
DECLARE changed INTEGER;
SET changed = 0;
IF STRCMP(NEW.first_name, OLD.first_name) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.last_name, OLD.last_name) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.maiden_name, OLD.maiden_name) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.suffix, OLD.suf开发者_如何学编程fix) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.title, OLD.title) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.gender, OLD.gender) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.street, OLD.street) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.street2, OLD.street2) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.city, OLD.city) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.state, OLD.state) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.zip, OLD.zip) <> 0 THEN
SET changed = 1;
ELSEIF STRCMP(NEW.home_phone, OLD.home_phone) <> 0 THEN
SET changed = 1;
ELSEIF NEW.date_of_birth <> OLD.date_of_birth THEN
SET changed = 1;
END IF;
IF changed > 0 THEN
update other_table set updated = CURRENT_TIMESTAMP where id = NEW.id;
END IF;
END;
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That's how ELSEIF
works inherently. Once MySQL finds any condition that passes (i.e., evaluates to TRUE) it will not evaluate any further conditions in the IF..ELSEIF..ELSE chain.
Try a CASE statement ...
SET changed = CASE
WHEN STRCMP(NEW.first_name, OLD.first_name) <> 0 THEN 1
WHEN STRCMP(NEW.last_name, OLD.last_name) <> 0 THEN 1
WHEN STRCMP(NEW.maiden_name, OLD.maiden_name) <> 0 THEN 1
...
ELSE 0
END
What about one monster OR
-ing? it would mean only one if-statement ;)
IF STRCMP(NEW.first_name, OLD.first_name) <> 0 or
STRCMP(NEW.last_name, OLD.last_name) <> 0 or
STRCMP(NEW.maiden_name, OLD.maiden_name) <> 0 or ...
...
SET changed = 1;
end if;
IF changed > 0 THEN
update other_table set updated = CURRENT_TIMESTAMP where id = NEW.id;
END IF;
...but seriously, your code is fine. Nothing to worry about. VoteyD was right.
The only other way to clean this up would be to remove some of these conditions - though it's probably not an option.
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