Question

I have a table:

table Event
- name
- description
- date (in format 2011-08-06 11:00:00)
- id

I need to create recurring events.

How can I best duplicate a row with mostly the same data (name, description) but change the date?

Say, if I have an event that occurs August 6th, I would like to create three more events on
– August 13, 20, 27 (every Saturday)

Also, is this something better accomplished with a mySQL query? I am guessing so because of the format the date is in…but any advice would be appreciated.

Answer 1

MySQL lacks a generator functionality (which would allow to create arbitrary length recordsets from scratch), so if the number of records is fixed, you could do something like that:

INSERT
INTO    event (name, description, date)
SELECT  name, description, date + INTERVAL n WEEK
FROM    (
        SELECT  1 AS n
        UNION ALL
        SELECT  2 AS n
        UNION ALL
        SELECT  3 AS n
        ) q
JOIN    event
ON      id = $myid

As you can see, the query layout depends on the number of events to create, with pure SQL there is no way to parameterize it.

You, however, can create a stored procedure and just call INSERT in a loop:

CREATE PROCEDURE prc_fill_event (p_id INT, p_cnt INT)
BEGIN
        DECLARE _cnt INT;
        SET _cnt = 1;
        WHILE _cnt <= p_cnt DO
                INSERT
                INTO    event (name, description, date)
                SELECT  name, description, date + INTERVAL _cnt WEEK
                FROM    event
                WHERE   id = p_id;
                SET _cnt = _cnt + 1;
        END WHILE;
END