What does $$ sign means in mysql?

Question

In MySQL query, what does the $$ signify?

DELIMITER $$
CREATE TRIGGER before_population_update
BEFORE UPDATE ON City
FOR EACH ROW BEGIN
INSERT INTO City_Changes
SET ACTION = ‘update’,
CityID = OLD.ID,
Population = OLD.Population,
User = USER(),
ChangedOn = NOW();
END $$
DELIMITER ;

mysql default delimiter is ; and your defining some other delimiter in above trigger definition $$ — Mahesh Madushanka, Jun 29 '16 at 07:05
You are defining it as a delimiter in the first line. What do you think it means? It has no special meaning. — TZHX, Jun 29 '16 at 07:06
that will help you to paste all the text untill it $$ to execute in single block — Mahesh Madushanka, Jun 29 '16 at 07:06
i think this question should exist, but still be marked as a duplicate. if you didn't know that `$$` was a delimiter, you wouldn't know to search for that and instead search for the title of this question. — SovietFrontier, Sep 04 '19 at 15:37

score 4 · Accepted Answer · answered Jun 29 '16 at 07:08

Triggers and stored procedures are [potentially] made up of several statements, which are each terminated by ;. Since ; is used to terminate an individual statement, they need a way to indicate the procedure/trigger is done - and this is where the delimiter command comes into play.

On the first row, we define the following trigger will be delimited (ended) by the $$ sequence. We then go on to declare a trigger (starting with create trigger and ending with $$ as we defined). Then, on the last row, we reset the delimiter to the default ; for good measures.

What does $$ sign means in mysql?

1 Answers1