如何使用php函数从数据库中提取数据

Question

This is what I have in my main page:

$foo = new Foo();
$strQry=$foo->Client();
$user_data=mysql_fetch_object($user_res);
echo $user_data->clientid;

This is what I have in my class file:

class Foo
{
function Client() 
{
$strQry = "SELECT clientid FROM users";
$user_res = mysql_query($strQry) or die("Unable to select, Error: ".mysql_error());
return $user_res;
}
}

I am not very good at using classes and functions with PHP and so I'm getting this error "Unable to select, Error: Access denied for user 'nobody'@'localhost' (using password: NO)"

Any help would be greatly appreciated!

Answer 1

It looks like you are not even making a connection to the database.

Here's a nice step-by-step walk through, that should show you how to connect to a mysql database using either mysqli or pdo, which are both more safe ways to talk to mysql.

http://codular.com/php-mysqli

Answer 2

There aa number of issues with your code:

• You should not be using mysql_* functions. They are deprecated. If you are just learning about using PHP with databases, do it the right way and use mysqli or PDO .
• You need to make sure you are actually connecting to the database. Maybe you are and it is not shown here, but this is obviously critical.
• You are intending to return a database result from your Client() method call. But you are not using the variable your returned the results into.

This code:

$strQry=$foo->Client();
$user_data=mysql_fetch_object($user_res);

Should be:

$strQry=$foo->Client();
$user_data=mysql_fetch_object($strQry);

because $strQry gets the result set resource.

• You are only calling mysql_fetch_object() once. You could have any number of rows in the result set based on your query. If you want all of them, you would need to loop through the result set and call mysql_fetch_object() on each row.

Perhaps something like this:

$user_data= array();
while($row = mysql_fetch_object($strQry)) {
    $user_data[] = $row;
}

• If you INSIST on using deprecated mysql_* functions, you might at least want to get in the habit of passing the DB connection as a parameter in your functions, to make it clear which DB connection you are working with.

So do something like:

mysql_query($strQry, $dbConn);