使用PHP無法從MySQL中的表中獲取最大ID

Question

您好，我想從MySQL表中獲取最大ID號，我寫道：

<?php
$servername='localhost';
$username='root';
$password='';
$databasename='myDB';
$con = new mysqli($servername,$username,$password,$databasename);
$max_id= $con->query('SELECT max(id) from myTable');
echo "<pre>";
print_r($max_id);
echo "</pre>";

但是$ max_id成為對象，輸出像這樣

mysqli_result Object
(
    [current_field] => 0
    [field_count] => 1
    [lengths] => 
    [num_rows] => 1
    [type] => 0
)

Answer 1

<?php
 $servername='localhost';
 $username='root';
 $password='';
 $databasename='myDB';
 $con = new mysqli($servername,$username,$password,$databasename); 
 $result= $con->query("SELECT max(id) from myTable");
 $max_id= mysqli_fetch_array($result);
 echo "<pre>";
 print_r($max_id);
 echo "</pre>rrr";
?>

Answer 2

您需要在查詢后獲取結果。 請在這里閱讀手冊： https : //secure.php.net/manual/en/mysqli.examples-basic.php

並且在閱讀正式文檔之前不要問任何問題。