Question

所以我试着在插入之前检查一下steamid64是否已经准备就绪，但它只是插入任何方式？我在这里不擅长PHP。

<?php
$con=mysqli_connect("localhost","user","pass","Gmod");

if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$SteamID64 = mysqli_real_escape_string($con, $_POST['SteamID64']);
$enable = mysqli_real_escape_string($con, $_POST['enable']);

$sql="SELECT * FROM Loading (SteamID64, enable) WHERE SteamID64='$SteamID64'";
 if(mysql_num_rows($sql)>=1) {
echo'<center>The music is already disabled!</center>';
}
else {
$sql="INSERT INTO Loading (SteamID64, enable)
VALUES ('$SteamID64', '$enable')";
}

if (!mysqli_query($con,$sql)) {
  die('Error: ' . mysqli_error($con));
}
echo "<center>The music will not play when you connect.</center>";

mysqli_close($con);
?>

我从一些论坛和w3schools.com上得到了这个并编辑了它。

好的，所以我做了这个，但它仍然只是插入数据？

<?php
mysqli_report(MYSQLI_REPORT_STRICT);
$con=mysqli_connect("localhost","root","server","Gmod");
if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$SteamID64 = mysqli_real_escape_string($con, $_POST['SteamID64']);
$enable = mysqli_real_escape_string($con, $_POST['enable']);

mysqli_query($con,"SELECT * FROM Loading WHERE SteamID64='$SteamID64'");
 if(mysqli_num_rows(mysqli_query)>=1) {
echo'<center>The music is already disabled!</center>';
}
else {
mysqli_query($con,"INSERT INTO Loading (SteamID64, enable)
VALUES ('$SteamID64', '$enable')");
}
echo "<center>The music will not play when you connect.</center>";

mysqli_close($con);
?>

Answer 1

除了你不能混合mysql_*和mysqli_*这样的功能（选择一个，mysqli_*并坚持下去）之外，你的sql中有一个错误：

SELECT * FROM Loading (SteamID64, enable) WHERE SteamID64='$SteamID64'
                      ^^^^^^^^^^^^^^^^^^^ this should not be here

您需要将其更改为：

SELECT * FROM Loading WHERE SteamID64='$SteamID64'

你可以让mysqli抛出异常，以便它在出错时告诉你到底出了什么问题。只需将其添加到脚本的顶部：

mysqli_report(MYSQLI_REPORT_STRICT);

您遇到的另一个问题是，您的第二个查询的执行应该在上一个条件的else部分内。

正如@FabrícioMatté已经提到过的，你实际上需要使用mysqli_query()执行查询，只是设置字符串不会做任何事情。

所以我试着让它检查一下，在插入之前看看steamid64是否已经准备就绪，但它只是插入任何方式？

1 个答案: