How to populate advanceddatagrid with hierarchical data using php and MySQL?

Following is the hierarchy supposed to go in the grid

Project 1
         Well 1
         Well 2
         Well 3
Project 2
         Well 4
         Well 5
Project 3
         Well 6
         Well 7
         Well 8


I have two tables Projects and Wells in my db with a fk in wells table relating to the project_id

Projects table
project_id       project_name
1                     Project 1
2                     Project 2
3                     Project 3

Wells table
well_id           well_name        projects_project_id
1                     Well 1               1
2                     Well 2               1
3                     Well 3               1
4                     Well 4               2
5                     Well 5               2
6                     Well 6               3
7                     Well 7               3
8                     Well 8               3

I want to modify the following function to get hierarchical data
 

public function getAllProjectsAndWells() {

		$stmt = mysqli_prepare(
					$this->connection, "SELECT project_id, project_name, well_name 
					FROM projects, wells 
					WHERE projects.project_id = wells.projects_project_id");		
		$this->throwExceptionOnError();
		
		mysqli_stmt_execute($stmt);
		$this->throwExceptionOnError();
		
		$rows = array();
		
		mysqli_stmt_bind_result($stmt, $row->project_id, $row->project_name, $row->well_name);
		
	    while (mysqli_stmt_fetch($stmt)) {
	      $rows[] = $row;
	      $row = new stdClass();
	      mysqli_stmt_bind_result($stmt, $row->project_id, $row->project_name, $row->well_name);
	    }
		
		mysqli_stmt_free_result($stmt);
	    mysqli_close($this->connection);
	
	    return $rows;
	}

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Also How can I populate the grid with this array?

Regards,
Salamay