添加auto_increment id列后，无法使用php和javascript将数据添加到mysql数据库

Question

I am creating a simple form using php, mysql and javascript. The idea is to have the user input the text, then the text is saved to the database, at the same time the latest text that the user have input returns from the database and shows on the same page without refreshing the page. The submitting function worked before I manually added the id column to the table. Please take a look of my codes and help me fix it, thank you.

submit.php ↓

<?php

$conn = mysql_connect('localhost','root','') or die (mysql_error);
$db = mysql_select_db('qinglish_nihaoemilie') or die (mysql_error);

$lastname = $_POST['lastname'];
$table = 'emilieinfo_lastname';

mysql_query("INSERT INTO $table VALUES('$lastname',NULL)");

?>

return.php ↓

<?php

$conn = mysql_connect('localhost','root','');
$db = mysql_select_db('qinglish_nihaoemilie');

$res = mysql_query ("SELECT * FROM emilieinfo_lastname ORDER BY id DESC LIMIT 1");
$result = array();

while ($row = mysql_fetch_array($res)) {
    array_push($result, array('lastname' => $row[0]));
}

echo json_encode(array('result' => $result));
?>

Javascript ↓

$('.lastname-container i').click(function(){
    var lastnameInput = $('.lastname').val();
    var lastnameInputLength = lastnameInput.length;
    if (lastnameInputLength > 0) {
        $('.lastname').hide();
        $(this).hide();
        var data = {
        lastname: $('.lastname').val(),
        };
        $.ajax({
            type: "POST",
            url: "../php/submitinfo-lastname.php",
            data: data,
        });

        $(this).parent().parent().find('p .fa-pencil-square-o').addClass('inline-table');
        $(this).parent().parent().find('p .fa-pencil-square-o').show();

        // $.getJSON("../php/returninfo-lastname.php", function(result){
        //  $.each(result, function(i, lastname){
        //      $(this).parent().parent().find('span').append(lastname + '');
        //  });
        // });

        // $.getJSON("../php/returninfo-lastname.php", function(returndata){
        //  $.each(returndata.result, function(){
        //      $(this).parent().parent().find('span').append("a"+this['lastname']);
        //  });
        // });
    };

    if (lastnameInputLength == 0) {
        $('.lastname').addClass('red-underline');
        $(this).addClass('red-color');
    };  
});

Database screenshot ↓

HTML ↓

<h2>
    <p>last name: 
        <span></span> 
        <i style="position:static; display: none;padding-left:5px;" class="fa fa-pencil-square-o"></i>
    </p>
    <div class="lastname-container">
        <input class="lastname" name="lastname" type="text">
        <i class="fa fa-check-square-o"></i>
    </div>
</h2>

Answer 1

Should your query not look something like this

mysql_query('INSERT INTO '.$table.' VALUES("'.$lastname.'")');

Also maybe try running your query in the mySQL SQL window to make sure your query actually works

Answer 2

检查此查询

mysql_query("INSERT INTO $table (lastname,id) VALUES('$lastname',NULL)");

Answer 3

mysql_query('INSERT INTO `emilieinfo_lastname`(`lastname`) VALUES('{$lastname}'));

只需删除id和NULL值，因为它是一个AUTO_INCREMENT字段，您可以在INSERT数据时将其删除。