Drupal - How to set 'INSERT IGNORE' in db_insert without db_merge

You've got two options:

1. Subclass InsertQuery and add that functionality in yourself (it's currently not implemented)
2. Use db_query() to run a raw SQL string instead.

The only mention of INSERT IGNORE in the Drupal 7 codebase is in DatabaseConnection_mysql:nextId; it's not actually used, but in its place is a raw query string containing ON DUPLICATE KEY UPDATE, that gets passed directly to db_query().

I may be wrong, but I'd assume that's as good an indication as any that a raw SQL string along with db_query() is the way to go.

Although it's not possible to use "INSERT IGNORE", there is a way you can get around this in PHP. Something like this:

try {
    $insertID = db_insert('crawl_data')->fields(array(
        'url' => $url, 
    ))->execute();
} catch (Exception $ex) {

}

In this example I have a database of "urls". But i dont want to first do a check if the item is in the database. I want it to happen in one go. So this is sort of the same behaviour as "insert ignore".

However, it's generally bad to have this:

catch (Exception $ex) {
    // open space
}

So it might be better to do this:

catch (Exception $ex) {
    $error = $ex->getMessage();
    if (strpos($error, 'SQLSTATE[23000]: Integrity constraint violation') !== false) {
        // then we know it's an error we can ignore
    }
    else {
        // just throw the error again
        throw $e;
    } 
}

It's either this or doing two database queries.