SELECT * FROM `sheets`, `group`, `disciplines` WHERE id_lecturers=1 AND group.id=sheets.id_group AND disciplines.id=sheets.id_disciplines

$string_query = "SELECT * FROM `sheets`, `group`, `disciplines` WHERE id_lecturers=$id AND group.id=sheets.id_group AND disciplines.id=sheets.id_disciplines";	

$result = mysqli_query( $link, $string_query ) or die("Ошибка: " . mysqli_error($link)); 


while ($line = mysqli_fetch_ASSOC($result)) {

   echo "<div>";
			
   foreach($line as $col_value) {
   
        echo " ".$col_value."";
   }
	
   echo "</div>";

}

$string_query = "SELECT group.name, disciplines.name as disciplinesName FROM `sheets`, `group`, `disciplines` WHERE id_lecturers=$id AND group.id=sheets.id_group AND disciplines.id=sheets.id_disciplines";