$ _GET和table.php？ini = ABC

I am trying to get a input from user which will then pull data from table and display it .

My code is

$ini = $_GET["ini_id"];
$con=mysqli_connect("localhost","root","","globalgoals");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
else

{
    $country = array();
    //country
    $sql="";
 //!mysqli_query($con,$sql))
    $result = mysqli_query($con,"SELECT * FROM country WHERE metrics="$ini");/*table name*/
    while($row = mysqli_fetch_array($result))
    {
        array_push($country,$row['country']);/*column name*/
    }
    //

When I enter the url http://localhost/xampp/testing/Int/table.php?ini=C2C

I get the error

Notice: Undefined index: ini_id in C:\xampp\htdocs\xampp\Testing\Int\table.php on line 2

In here your trying to get like this $_GET['ini'];

http://localhost/xampp/testing/Int/table.php?ini=C2C

If your trying to get it like $_GET['ini_id']

http://localhost/xampp/testing/Int/table.php?ini_id=C2C //change here

Get $ini = $_GET["ini"]; because you did not passed ini_id.

Second

$result = mysqli_query($con,"SELECT * FROM country WHERE metrics='".$ini."'");

one more thing,

$result = mysqli_query($con,"SELECT * FROM country WHERE metrics='".$ini."'");

You missed the dot before and after the variable.

Use isset...

$ini = (isset($_GET['ini_id'])) ? $_GET['ini_id'] : null;

But perhaps more importantly, you need to secure that variable before you use it as part of a database query. Since your id is alphanumeric use mysqli_real_escape_string():

$ini = (isset($_GET['ini_id']) ? $_GET['ini_id'] : null;
$ini = mysqli_real_escape_string($con, $ini);