将$ result更改为MySQLi或PDO PHP [复制]

Question

This question already has an answer here:

• Why shouldn't I use mysql_* functions in PHP? 15 answers

When i use this code. It says:

Database access failed: no database selected"

And it also gives the:

Deprecated: mysql_query(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead

error. The following is the code i have used.

$con = mysqli_connect("localhost", "root", "","radian")
    or die ("Couldn't connect to  mySQL");  


$query = "SELECT Staff_id,Fname,Sname,Gender,username FROM staff  ";

$result = mysql_query($query);
if (!$result) die ("Database access failed: " . mysql_error());
$rows = mysql_num_rows($result);
for ($j = 0 ; $j < $rows ; ++$j)


{
    $row = mysql_fetch_array($result);
    $staff_id = $row['Staff_id'];
    $Fname = $row['Fname'];
    $Sname = $row['Sname'];
    $Gender = $row['Gender'];
    $username = $row['username'];

    echo '<tr> <td>'.$staff_id.'</td> <td>'.$Fname.'</td> <td>'.$Sname.'</td> <td>'.$Gender.'</td> <td>'.$username.'</td> </tr>';
}

It says the error is from this line:

$result = mysql_query($query);

</div>

Answer 1

You are using mysql in place of mysqli, and mysqli needs connection with the query.

Just Replace you code with this one:

$con = mysqli_connect("localhost", "root", "","radian")
    or die ("Couldn't connect to  mySQL");  


$query = "SELECT Staff_id,Fname,Sname,Gender,username FROM staff  ";

$result = mysqli_query($con, $query);
if (!$result) die ("Database access failed: " . mysqli_error($con));
$rows = mysqli_num_rows($result);
for ($j = 0 ; $j < $rows ; ++$j)


{
    $row = mysqli_fetch_array($result);
    $staff_id = $row['Staff_id'];
    $Fname = $row['Fname'];
    $Sname = $row['Sname'];
    $Gender = $row['Gender'];
    $username = $row['username'];

    echo '<tr> <td>'.$staff_id.'</td> <td>'.$Fname.'</td> <td>'.$Sname.'</td> <td>'.$Gender.'</td> <td>'.$username.'</td> </tr>';
}