public function subQuery( $table, $alias=null )
    {
        $sub = new self();
        if( !$alias ) $alias = 'sub_' . $this->subQueryCount ++;
        $sub->table( $table, $alias );
        $sub->setParentTable( $this->getAliasOrTable() );
        return $sub;
    }
public function subQuery( $table, $alias=null )
    {
        $sub = new self();
        if( !$alias ) $alias = 'sub_' . $this->subQueryCount ++;
        $sub->table( $table, $alias );
        $sub->setParentTable( $this->getAliasOrTable() );
        return $sub;
    }
public function subQuery ( $ table , $ alias = null ) { $ sub = new self ( ) ; if ( ! $ alias ) $ alias = 'sub_' . $ this -> subQueryCount ++ ; $ sub -> table ( $ table , $ alias ) ; $ sub -> setParentTable ( $ this -> getAliasOrTable ( ) ) ; return $ sub ; }
return a new Sql|Query object as sub-query.

@param string $table
@param string $alias
@return $this
return a new Sql|Query object as sub - query .