Php mysql中的减量变量为1

输入列车ID

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删除查询$availablesatsac中分配给empty的两个
$
符号？使用列名代替这些变量。这是一个印刷错误；这样投票。您的代码也受SQL注入的约束。如果您重视投入的时间和数据，请使用准备好的语句。
<?php include('railways.php')?>
<form action='' method='POST'>
<p>Enter trainid </p>
<input type="text" name="trainid"/>
<input type="submit" name="submit"/>
</form>

<?php
if(isset($_POST['submit'])){
$availableSeatsAC="";
$bookedSeatsAC = "";
$id = $_POST['trainid'];
$query = "UPDATE trainstatus SET ";
$query .= "availableSeatsAC = $availableSeatsAC-1, ";
$query .= "bookedSeatsAC = $bookedSeatsAC+1 ";
$query .= "WHERE trainid = '$id'";
$result = mysqli_query($connection , $query);
if(!$result){
  die('QUERY FAILED'.mysqli_error($connection));
   }
   else{
    echo "CORRECTLY WORKED";

   }
}
?>

<?php
if(isset($_POST['submit'])){
$id = $_POST['trainid'];
$query = "UPDATE trainstatus SET ";
$query .= "availableSeatsAC = availableSeatsAC-1, ";
$query .= "bookedSeatsAC = bookedSeatsAC+1 ";
$query .= "WHERE trainid = '$id'";
$result = mysqli_query($connection , $query);
if(!$result){
  die('QUERY FAILED'.mysqli_error($connection));
   }
   else{
    echo "CORRECTLY WORKED";

   }
}
?>