Removed dead code, `explode` will only return `false` if delimiter is empty string. In such a case `explode` will trigger warning

model/SqlDbDriver.php

@@ -109,9 +109,6 @@ abstract class SqlDbDriver extends DbDriver
     public function quoteIdentifier($ident)
     {
         $ident = explode('.', $ident);
-        if (!is_array($ident)) {
-            $ident = array($ident);
-        }
         foreach ($ident as &$segment) {
             $segment = $this->identifier_quote . $segment . $this->identifier_quote;
         }