php函数Mysql输出错误

Question

My code is as follows:

class Database  
{  
    private $db_host;  
    private $db_user;  
    private $db_pass;  
    private $db_name;  
    private $con;

    public function __construct() {
        $this->db_host = "localhost";  
        $this->db_user = "admin";  
        $this->db_pass = 'password';  
        $this->db_name = 'test';    
        $this->con = '';
    }

    public function connect() {
        $db_name = "test";    
        $this->con = mysql_connect($this->db_host, $this->db_user, $this->db_pass);
    }  

    public function select(){
        $q = "SELECT name, city FROM customers;";
        mysql_select_db($this->db_name, $this->con);
        $result = mysql_query($q);
        return mysql_fetch_assoc($result);
    }  
} 


$db = new Database();
$db->connect();
$tempArray = Array();
$rs = $db->select('customers', 'name, suburb');
foreach ($rs as $row)
{
    echo $rs['name'] . "<br>";
}

And my table's data is

name | city
--------------
Anne | Sydney
Jane | London

The actual output is:

Anne 
Anne

The desired output is:

Anne
Jane

Can someone tell me what I am doing wrong. It seems like I have missed something basic. I have read over 50 articles and nothing seems to explain what I am doing wrong.

Note: This is a scaled down version of my code. I intend to use this to make a more general object that pulls information from my database.

Thanks,

Brett

Answer 1

You need to call mysql_fetch_assoc for each row. It only returns one row of data, not the full set. For example, you could move it out into the loop:

class Database
{  
    /* ... */

    public function select(){
        $q = "SELECT name, city FROM customers;";
        mysql_select_db($this->db_name, $this->con);
        return mysql_query($q);
        /* Remove your line here, returning the query result, not the first row */
    }  
} 

$db = new Database();
$db->connect();
$tempArray = Array();
$result = $db->select('customers', 'name, suburb');
/* Note that I'm now using mysql_fetch_assoc to get each row from the result */
while ($row = mysql_fetch_assoc($result));
    echo $row['name'] . "<br>";
}

You can use a while loop there because after the last row has been retrieved, mysql_fetch_assoc will return FALSE and exit the loop.

Answer 2

In this section of your code:

return mysql_fetch_assoc($result);

You are merely returning the first row. I suggest you to create an array.

public function select(){
    $q = "SELECT name, city FROM customers;";
    mysql_select_db($this->db_name, $this->con);
    $result = mysql_query($q);
    $toReturn = array();
    while($row = mysql_fetch_assoc($result) )
        $toReturn[] = $row;
    return $toReturn;
}

Answer 3

Should'nt it be :

foreach ($rs as $row)
{
    echo $row['name'] . "<br>";
}

And:

$resArr = array();
while($res = mysql_fetch_assoc($result)) {
  $resArr[] = $res;
}
return $resArr;

Answer 4

A sane version of your class. It lacks vital parts of course, to be used in the real life, but just out of your sketch:

class Database  
{  
    private $con;

    public function __construct() {
        $this->con = mysql_connect("localhost", "admin", 'password');
        mysql_select_db("test",$this->con);
    }
    public function query($sql,$this->con){
        return mysql_query($sql);
    }  
    public function get_all($sql,$this->con){
        $ret = array();
        $res = mysql_query($sql);
        while  ($row = mysql_fetch_array($row)) {
          $ret[] = $row;
        }
        return $ret;
    }  
} 

$db = new Database();
$rs = $db->get_all("SELECT name, city FROM customers");
foreach ($rs as $row)
{
    echo $rs['name'] . "<br>";
}

Answer 5

Seems kind of odd that no one has picked up on a bit of a gaff in the code here.

You define select() like so:

public function select(){
    $q = "SELECT name, city FROM customers;";
    mysql_select_db($this->db_name, $this->con);
    $result = mysql_query($q);
    return mysql_fetch_assoc($result);
}

But, then you call it like this:

$rs = $db->select('customers', 'name, suburb');

I assume your intention was to be able to specify the table and the fields to select from the database. If it was, your select function should look more like this:

public function select($table, $fields){
    $q = "SELECT $fields FROM $table;";
    mysql_select_db($this->db_name, $this->con);

    return mysql_query($q);
} 

From there you would follow @BenLee's example in his answer, since you need to iterate over a resultset. Each field becomes a key in an associative array.

I wouldn't recommend actually doing string insertion like this in production code, but I think it's closer to what you intended.

HTH.