PHP Unlimited classification using concat How to achieve _php skills

First, the database design

---  
table structure for table ' category '- 
-  
 
CREATE Table ' category ' ( 
 ' id ' int (one) not NULL Auto_increme NT, 
 ' catpath ' varchar (255) default NULL, 
 ' name ' varchar (255) default NULL, 
 PRIMARY KEY (' id ') 
engine= MyISAM DEFAULT Charset=utf8 auto_increment=11; 
 
---  
dumping data for table ' category '- 
-  
 
inserts into ' category ' VALUES (1, ' 0 ', ' homepage '); 
INSERT into ' category ' VALUES (2, ' 0-1 ', ' Linux OS '); 
INSERT into ' category ' VALUES (3, ' 0-1 ', ' Apache server '); 
INSERT into ' category ' VALUES (4, ' 0-1 ', ' MySQL database '); 
INSERT into ' category ' VALUES (5, ' 0-1 ', ' PHP scripting language '); 
INSERT into ' category ' VALUES (6, ' 0-1-2 ', ' Linux system Tutorial '); 
INSERT into ' category ' VALUES (7, ' 0-1-2 ', ' Linux Network Technology '); 
INSERT into ' category ' VALUES (8, ' 0-1-2 ', ' Linux security Basics '); 
INSERT into ' category ' VALUES (9, ' 0-1-2-7 ', ' Linux LAMP '); 
INSERT into ' category ' VALUES (Ten, ' 0-1-3-10 ', ' Apache Server ');  

In this note, the Catpath-link symbol is not fixed, you can choose, such as special symbols.

Second, the PHP code implementation

? 
$conn = mysql_connect (' localhost ', ' root ', ' root '); 
mysql_select_db (' Test ', $conn); 
mysql_query (' Set names UTF8 '); 
$sql = "Select Id,concat (Catpath, '-', id) as Abspath,name from category order by Abspath"; 
$query = mysql_query ($sql); 
while ($row = Mysql_fetch_array ($query))  
{ 
  //First Presentation method 
  //$space = Str_repeat (', Count (explode) (' -', $row [' Abspath '])-1); 
  Echo $space. $row [' name ']. ' <br> '// 
   
  Second Presentation method 
  $space = Str_repeat (', Count (Explode ('-', $row [' Abspath '])-1); 
  $option. = ' <option value= '. $row [' id ']. ' > '. $space. $row [' name ']. ' </option> '; 
} 
Echo ' <select name= ' opt ' > '. $option. ' </select> '; 

The MySQL concat function can connect one or more strings

Select Concat (' Yan ', ' pei ', ' Climb ')
select ' id ', ' name ', concat (' id ', '-', ' name ') as Iname

The above is the whole content of this article, introduced the PHP uses concat realizes the wireless classification, hoped for everybody's study to have the help.