致命错误：在$ run = $ con - ＆gt;中对非对象调用成员函数query（）查询（$查询）;

Question

<?php

$name= $_POST['name'];
$roll= $_POST['roll'];

$con= mysql_connect("localhost", "root","");
mysql_select_db("students");

$query = "update classmate SET name= '$name' where roll= $roll";
echo $query;

$run = $con -> query($query);
if($run){
    echo "data Has been Updated";

}
 else {
     echo "Data Has not Updated";
 }

?>

错误是：

  

致命错误：在$ run = $ con - ＆gt;中的非对象上调用成员函数query（）查询（$查询）;

Answer 1

要捕获连接错误，您可以使用try-catch块：

try {
    $con= mysql_connect("localhost", "root","");
} catch (Exception $e) {
    echo 'Error: ' . $e->getMessage();
}

Answer 2

您可以使用此代码：

$name= $_POST['name'];
$roll= $_POST['roll'];
$con= mysqli_connect("localhost", "root","","students");
$query = "update classmate SET name= '$name' where roll= $roll";
echo $query;
$run = mysqli_query($con, $query);
if($run){
  echo "data Has been Updated";
} else {
  echo "Data Has not Updated";
}