A question from comp.lang.php:
I have a MySQL table of pages each with a ‘title’ and ‘page’ fields.
How do I do either an UPDATE if the pages ‘title’ exists or an INSERT if it does not?
Assuming that `title` is a primary or unique key, it’s very simple:
INSERT INTO `pages` (`title`, `page`)
VALUES ('My Title', 'My Page')
ON DUPLICATE KEY UPDATE `page`='My Page'
See MySQL documentation for more information:
http://dev.mysql.com/doc/refman/4.1/en/insert.html
Alternatively, you can issue a REPLACE query:
http://dev.mysql.com/doc/refman/4.1/en/replace.html
The difference is that with INSERT … ON DUPLICATE KEY UPDATE, you can update an existing record partially (i.e., if there are fields other than `title` and `page`, they will be kept intact). REPLACE, however, deletes an existing row (if it exists, that is) before writing a new one, so any fields not explicitly set by the REPLACE query will be set to their default values.