Support for columns that are not part of the table(s); 
Support for columns that are not part of the table(s); 

$grid->getSelect()->columns(array('expr'=>new Zend_Db_Expr('CONCAT(field,field2)')));

zervel/grid,zfdatagrid/grid,zfdatagrid/grid,zfdatagrid/grid,zervel/grid,zfdatagrid/grid,zervel/grid