Compare dates in MySQL trigger - mysql

Question

I have two tables, round and event. One round has many events.
create table round (
round_id INTEGER AUTO_INCREMENT NOT NULL,
round_start_date DATETIME NOT NULL,
round_end_date DATETIME NOT NULL,
CONSTRAINT round_pk PRIMARY KEY (round_id)
);
create table event (
event_id INTEGER AUTO_INCREMENT NOT NULL,
round_id INTEGER NOT NULL,
event_date DATETIME NOT NULL,
CONSTRAINT event_pk PRIMARY KEY (event_id),
CONSTRAINT round_fk FOREIGN KEY (round_id) REFERENCES round (round_id),
);
When a row is inserted into the event table, I want to use a trigger to compare the event_date field of the newly inserted row to the round_start_date and round_end_date fields in its corresponding entry in the round table. If event_date is earlier than round_start_date, round_start_date should be updated with the new event_date. If event_date is after round_end_date, round_end_date should be updated with the new event_date.
This is my trigger. It does not work, and I do not understand why. I cannot find anywhere on the web where anyone else has tried to use a datetime type in a trigger, so I have no frame of reference for where I am going wrong.
create trigger update_round_date
after insert on event for each row
begin
declare curSdate datetime;
declare curEdate datetime;
set curSdate = (select round_start_date from round where round_id = NEW.round_id);
set curEdate = (select round_end_date from round where round_id = NEW.round_id);
if (NEW.event_date < curSdate) then
update round set round_start_date = NEW.event_date where round_id = NEW.round_id;
else if (NEW.event_date > curEdate) then
update round set round_end_date = NEW.event_date where round_id = NEW.round_id;
end if;
end;
EDIT: I simply can't create the trigger. phpMyAdmin gives me this error:
"#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 4"
EDIT 2: Updated with a delimiter set
DELIMITER $$
create trigger update_round_date
after insert on event for each row
begin
declare curSdate datetime;
declare curEdate datetime;
set curSdate = (select round_start_date from round where round_id = NEW.round_id);
set curEdate = (select round_end_date from round where round_id = NEW.round_id);
if (NEW.event_date < curSdate) then
update round set round_start_date = NEW.event_date where round_id = NEW.round_id;
else if (NEW.event_date > curEdate) then
update round set round_end_date = NEW.event_date where round_id = NEW.round_id;
end if;
end$$
This returns the error: "#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 13"

Answer 1

MySQL is probably stopping at the first ';', interpreting your command as:
create trigger update_round_date
after insert on event for each row
begin
declare curSdate datetime;
You have to set your delimiter to something else first, then terminate the create trigger command with that delimiter instead (and put the delimiter back at the end):
delimiter ^
create trigger update_round_date
after insert on event for each row
begin
...
end;
^
delimiter ;
I believe the last semicolon after end may be necessary.

Answer 2

There may be a problem with delimiters in phpmyadmin, try to use this trigger -
CREATE TRIGGER trigger1
AFTER INSERT
ON event
FOR EACH ROW
UPDATE
round
SET
round_start_date =
IF(NEW.event_date < round_start_date, NEW.event_date, round_start_date),
round_end_date =
IF(NEW.event_date > round_end_date, NEW.event_date, round_end_date)
WHERE
round_id = NEW.round_id;