Set up drop-down menu in excel and implement multi-level tree menu with PHP

//Tree directory structure template program
//Menu directory library field description:
//menu_id menu item id
//menu menu name
//menu_grade menu level 1 is the main menu and 2 is the secondary menu. .......
//menu_superior menu id number
function my_menu($menu_content,$i,$menu_grade_temp,$menu_superior_temp)
{ global $PHP_SELF;
$temp1=$menu_grade_temp+1;
$menu_superior_temp_array=split("/",$menu_superior_temp);
for ($t=0;$t<$i;$t++)
{
$menu_array=split("/",$menu_content[$t]);
If(($menu_array[2]==$menu_grade_temp)&&($menu_array[3]==$menu_superior_temp_array[$menu_grade_temp-1]))
                                              $p++){echo " ";}                     $temp3=$menu_superior_temp_array;                          If ($menu_array[ 0]==$menu_superior_temp_array[$temp1-1])                                                                                                                                                         $temp5           ("/",$temp3);
echo "$menu_array[1]
";
my_menu($menu_content,$i . temp3);                                                                           echo "$menu_array[1]
";
// Connect to MySql database
$ db_host="localhost";
$db_user="dkj";
$db_password="123";
$db_name="test";
mysql_connect($db_host,$db_user,$db_password);
mysql_select_d b($db_name);
//Get data from the database
$query_string="select * from menu order by menu_grade";
$db_data=mysql_query($query_string);
//Perform initialization for the first time
if ($menu_grade_temp=="")
{
$menu_superior_temp=0;
}
//Read all the information into the array and count the number of arrays
$i=0;
while (list($menu_id,$menu,$menu_grade,$menu_superior)=mysql_fetch_row($db_data))
{
$ menu_content[$i]=$menu_id."/".$menu."/".$menu_grade."/".$menu_superior;
$i++;
} my_menu($menu_content,$i,1,$menu_superior_temp) ;
/* Attached database structure and simulation data
# phpMyAdmin MySQL-Dump #
# Host: localhost Database: test
# ---------------------- ----------------------------------
#
# Data table structure 'menu'
# CREATE TABLE menu (
menu_id int(11) NOT NULL auto_increment,
menu varchar(20) NOT NULL,
menu_grade int(11) NOT NULL,
menu_superior int(11) NOT NULL,
UNIQUE menu_id (menu_id)
);
#
# Export the following database content 'menu'
#
INSERT INTO menu VALUES( '1', 'Computer', '1', '0');
INSERT INTO menu VALUES( '2', 'Programming', ' 2', '1');
INSERT INTO menu VALUES( '3', 'Network', '2', '1');
INSERT INTO menu VALUES( '4', 'PHP and MySql', '3' , '2');
INSERT INTO menu VALUES( '5', 'C language', '3', '2');
INSERT INTO menu VALUES( '6', 'Web page production', '3', ' 3');
INSERT INTO menu VALUES( '7', 'TCP, IP protocol', '3', '3');
INSERT INTO menu VALUES( '8', 'Mathematics', '1', '0 ');
INSERT INTO menu VALUES( '9', 'Advanced Mathematics', '2', '8');
INSERT INTO menu VALUES( '10', 'Linear Algebra', '3', '9') ;
INSERT INTO menu VALUES( '11', 'Discrete Mathematics', '3', '9');
INSERT INTO menu VALUES( '12', 'Elementary Mathematics', '2', '8');
INSERT INTO menu VALUES( '13', 'Literature', '1', '0');
INSERT INTO menu VALUES( '14', 'Chinese Literature', '2', '13');
INSERT INTO menu VALUES( '15', 'php', '4', '4');
INSERT INTO menu VALUES( '16', 'mysql', '4', '4');
*/
?>
The above introduces how to use PHP to implement multi-level tree menus in excel setting drop-down menus, including the content of excel setting drop-down menus. I hope it will be helpful to friends who are interested in PHP tutorials.