/**
  * Return the '<table> as <alias>' part for the SQL FROM clause
  * @return string 
  */
 public function getTableAlias()
 {
     // quote ids
     $table = $this->quoteId($this->cm->getTable());
     $alias = $this->quoteId($this->alias);
     // return sql
     return "{$table} AS {$alias}";
 }