Search with a ' quote causes SQL error

Searching a flexinode text field and including a ' in the query causes an SQL error similar to the following:

You have an error in your SQL syntax near 's grill%'OR
Where the search was: fred's grill

This is easily fixed by replacing ' with '' in the flexinode_page_table function:
Change:

    if ($edit['search']) {
      $sql .= " AND (n.title LIKE '%". $edit['search'] ."%'";
      foreach ($ctype->fields as $field) {
        $sql .= 'OR flexinode_'. $field->field_id .".textual_data LIKE '%". $edit['search'] ."%'";
      }
      $sql .= ')';
    }

To:

    if ($edit['search']) {
      $qsearch = str_replace("'", "''", $edit['search']);
      $sql .= " AND (n.title LIKE '%". $qsearch ."%'";
      foreach ($ctype->fields as $field) {
        $sql .= 'OR flexinode_'. $field->field_id .".textual_data LIKE '%". $qsearch ."%'";
      }
      $sql .= ')';
    }

However, this is almost certainly not the 'Drupal way' to do this - if anyone knows exactly which filter function this string needs to be run through to do this, please advise!

Thanks!
- Grugnog