Question

I am trying to create a Trigger for a table that UDATES. I thought I could do this with multiple Triggers but I guess MySQL does not support multiple triggers on one table for the same type. So I a forced to include this into one trigger.

Basically I have trying to insert a new record into a different table based on what is updated in the current table.

Here is what I have so far and it works:

BEGIN
-- Definition start
INSERT INTO prices (stationID, price, type, 
prevPrice, prevDate, dateCreated, apiKey, uid) 
VALUES(NEW.stationID, NEW.regPrice, 'reg', OLD.regPrice,
OLD.regDate, NEW.regDate, NEW.lastApiUsed, NEW.lastUpdatedBy);
-- Definition end
END

What I need to happen is the type may change based on what type the user gives. Since the user may only update one type at a given time. I was thinking about an IF IF THEN statement but I wasn’t sure how to get it to work. I was thinking I could use a String value of the column name to use in the IF statement but I an not sure if that is possible.

Something like this:

    BEGIN
    -- Definition start
    IF(type == 'reg') THEN
    INSERT INTO prices (stationID, price, type, 
    prevPrice, prevDate, dateCreated, apiKey, uid) 
    VALUES(NEW.stationID, NEW.regPrice, 'reg', OLD.regPrice,
    OLD.regDate, NEW.regDate, NEW.lastApiUsed, NEW.lastUpdatedBy);
    END IF;
    -- Definition end
    END

Answer 1

I was able to use IF THEN ELSE to complete the transaction. Then I tested the condition for a NULL value. If it is TRUE I then ran my code. Now for some reason it only does one INSERT command even though the UPDATE is for more than one. Any thoughts on this?

BEGIN
-- Definition start
IF(NEW.regPrice IS NOT NULL) THEN
INSERT INTO prices (stationID, price, type, 
prevPrice, prevDate, dateCreated, apiKey, uid) 
VALUES(NEW.stationID, NEW.regPrice, 'reg', OLD.regPrice,
OLD.regDate, NEW.regDate, NEW.lastApiUsed, NEW.lastUpdatedBy);

ELSEIF(NEW.midPrice IS NOT NULL) THEN
INSERT INTO prices (stationID, price, type, 
prevPrice, prevDate, dateCreated, apiKey, uid) 
VALUES(NEW.stationID, NEW.midPrice, 'mid', OLD.midPrice,
OLD.midDate, NEW.midDate, NEW.lastApiUsed, NEW.lastUpdatedBy);

ELSEIF(NEW.prePrice IS NOT NULL) THEN
INSERT INTO prices (stationID, price, type, 
prevPrice, prevDate, dateCreated, apiKey, uid) 
VALUES(NEW.stationID, NEW.prePrice, 'pre', OLD.prePrice,
OLD.preDate, NEW.preDate, NEW.lastApiUsed, NEW.lastUpdatedBy);
END IF;
-- Definition end
END