MySQL insert if table not exists

Question

I'll tried creating a little installation script for my modules. When I call $_GET["install"] the script is running. I looks like this:

public function install()
{
  $this->sql->query("
    INSERT
    INTO    cms_modules (title)
    VALUES  ('Guestbook')
  ");

  $this->sql->query("
    CREATE TABLE IF NOT EXISTS `cms_guestbook` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `name` varchar(255) NOT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;
  ");
}

It works pretty good. The table is installed and a new row is added to cms_modules, although I would like that the INSERT is only activated if the cms_guestbook table doesn't exists.

I searched for a answer and found this topic. I'll tried using that WHERE NOT EXISTS by doing the following:

$this->sql->query("
  INSERT
  INTO    cms_modules (title)
  VALUES  ('Guestbook')
  WHERE NOT EXISTS (
          SELECT 1 FROM cms_guestbook
  )
");

But this didn't worked for my. The table is installed, but the row not inserted. I also tried using SHOW TABLES LIKE but that also didn't seem to work.

Anyone suggestions or a solution?

Answer 1

You could do something like this:

if(!$this->sql->query("SHOW TABLES LIKE 'cms_guestbook'")){
    $this->sql->query("
        INSERT
        INTO    cms_modules (title)
        VALUES  ('Guestbook')
      ");
}

You query to see if it finds a specific table and if it returns false (check to be sure it returns a boolean) you run your other query.