How do you write a case insensitive query for both MySQL and Postgres?

Question

I\'m running a MySQL database locally for development, but deploying to Heroku which uses Postgres. Heroku handles almost everything, but my case-insensitive Like statements

Answer 1

There are several answers, none of which are very satisfactory.

• LOWER(bar) = LOWER(?) will work on MySQL and Postgres, but is likely to perform terribly on MySQL: MySQL won't use its indexes because of the LOWER function. On Postgres you can add a functional index (on LOWER(bar)) but MySQL doesn't support this.
• MySQL will (unless you have set a case-sensitive collation) do case-insensitive matching automatically, and use its indexes. (bar = ?).
• From your code outside the database, maintain bar and bar_lower fields, where bar_lower contains the result of lower(bar). (This may be possible using database triggers, also). (See a discussion of this solution on Drupal). This is clumsy but does at least run the same way on pretty much every database.