SELECT 
    t1.`text` AS  `txt1` , t2.`text` AS  `txt2` 
FROM  
    `exam` AS t1
LEFT JOIN  
    `rgr` AS t2 
    ON t2.`id` IN (SELECT  `id` 
                    FROM  `DATA_TEST` 
                    WHERE  `type_test` =  'exam' )
WHERE 
    t1.`id` IN (SELECT  `id` 
                FROM  `DATA_TEST` 
                WHERE  `type_test` =  'rgr')

//Получаю массив названий таблиц
$sql   = 'SELECT `type_test` FROM `date_test`';
$type_test = sqlArray($DB->query($sql));
//убираю  повторения
$type_test = array_unique($type);
$row = array();
foreach($type_test as $value)
       {
            $sql   = 'SELECT D.`type_test`, T.`id`, T.`text`,   D.`date`  
                        FROM `date_test` as D
                        LEFT JOIN `'.$value.'` as T ON(T.`id` = D.`id_test`)';
            
           $row +=sqlArray($DB->query($sql));
       }
Получаю, то что мне нужно:
type_test | id | text | date
exam-------2---- hello!--03
rgr----------14---- ya!---17

SELECT 
   t1.`type_test` , 
   t1.`id_test` , 
   t1.`date` ,
   t2.`text` AS  `exam_text` , 
   t3.`text` AS  `rgr_text` 
FROM  
  `DATA_TEST` AS t1
LEFT JOIN  
  `exam` AS t2 ON t1.`id_test` = t2.`id` 
LEFT JOIN  
  `rgr` AS t3 ON t1.`id_test` = t3.`id`