card/make/controller/doBan.php

<?php
$banner = $_POST['banner'];
$link = $_POST['link'];
$banner_one = $_POST['banner_one'];
$link_one = $_POST['link_one'];
$banner_two = $_POST['banner_two'];
$link_two = $_POST['link_two'];
$type = 'banner';

include_once("../../untils/conn.php");

if ($con) {
    mysqli_query($con, "set names utf8");
    
    // 查询数据库中的记录数
    $result = mysqli_query($con, "SELECT COUNT(*) FROM system WHERE id=1");
    $row = mysqli_fetch_row($result);
    $num_rows = $row[0];
    
    if ($num_rows == 0) {
        // 如果记录数为0，说明数据库中没有数据，执行插入新数据的操作
        $data = $con->query("INSERT INTO system (banner, link, type, banner_one, link_one, banner_two, link_two) VALUES ('$banner', '$link', '$type', '$banner_one', '$link_one', '$banner_two', '$link_two')");
    } else {
        // 如果记录数不为0，说明数据库中已经存在数据，执行更新操作
        $data = $con->query("UPDATE system SET banner='$banner', link='$link', type='$type', banner_one='$banner_one', link_one='$link_one', banner_two='$banner_two', link_two='$link_two' WHERE id=1");
    }
    
    if ($data > 0) {
        echo "<script>alert('修改成功');window.location.href='../Bansytem.php'</script> ";
    } else {
        echo ("<script>alert('修改失败');window.location.replace(document.referrer)</script>");
    }
}

$con->close();
?>