Use square brackets syntax in sql queries

I banged my head on this for an hour this morning, just to figure out it was Drupal killing my brackets and not a problem with my regex...

The answer is to add the 'allow_square_brackets' option to the query

`\Drupal::database()->select('table', 't', ['allow_square_brackets' => TRUE]);`

Unfortunately, my regex was `'[0-9]{2,}'`, and I don't see a way to preserve squiggly brackets as those are used as table placeholders by the query builder. I'll get around it with `'[0-9][0-9]+` for today, but it's good to realize I can't use squiggly brackets in regex.