PHP MySql试图获取最后一行的数量

Question

I've got a table with two columns "Number" and "Date". I want retrieve the value of the last row however this isn't working:

   $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 

    $sql = "SELECT Number FROM functions_order_numbers ORDER BY Number DESC LIMIT 1";
    $result = mysqli_query($conn, $sql);

    if (mysqli_num_rows($result) > 0) {
        while($row = mysqli_fetch_assoc($result)) {
    echo $row["Number"];
    }
mysqli_close($conn);

Table: Table Screenshot

I'm trying to create an incremental unique order number

Answer 1

If you want an incremental number in the table, then use auto_increment :

create table t (
    number int auto_increment primary key,  -- usually it is a primary key
    . . .
);

Don't attempt to do this at the application layer. It is dangerous, because multiple updates at the same time might not do the right thing.