REPLACE sql command

[pavarnos]

Hi

Would you accept a pull request that allowed the hard-coded "INSERT" statement in */Insert.php to be swapped for "REPLACE" when we need to do a REPLACE INTO query? (supported by sqlite, mysql)

Would probably implement it like this:

private $insertCommand = 'INSERT';

public function useReplace() 
{
    $this->insertCommand = 'REPLACE';
}

protected function build()
{
        return $this->insertCommand
            . $this->buildFlags()
            . $this->buildInto()
            . $this->buildValuesForInsert()
            . $this->buildValuesForUpdateOnDuplicateKey()
            . $this->buildReturning();
}

I prefer this approach over onDuplicateKeyUpdate() because it allows my tests to run unchanged on sqlite while using mysql on the live server. On Duplicate Key update is mysql only?

[pmjones]

I'd be happy to look at a PR for this, if you're willing to submit one! I'd figure it should use a flag on the useReplace() method so it could be switched back and forth. E.g., $insert->useReplace(false) would put it back to a regular insert.

[pmjones]

Also, it should probably be on the db-specific INSERT classes, not the common one.