Basic PHP/MYSQL debugging

There are a few things wrong here.

Firstly, this variable is invalid $field1-name.

PHP is interpreting that as doing math, such as "field1 MINUS name".

Use an underscore $field1_name and for all instances for it in your code.

and use error reporting.

Sidenote:

• Use mysqli_affected_rows().
• http://php.net/manual/en/mysqli.affected-rows.php

in order to be 100% sure of a successful query/insert and in conjunction with your error checking.

It's better than if ($conn->query($sql) === TRUE) but that's a matter of preference I guess.

You also have a missing semi-colon in

$field1-name =  mysqli_real_escape_string ( $conn , $_POST['field1-name'])
                                                                          ^ right there

which error reporting would have caught as a parse error.

• http://php.net/manual/en/function.error-reporting.php

Add error reporting to the top of your file(s) which will help find errors.

<?php 
error_reporting(E_ALL);
ini_set('display_errors', 1);

// rest of your code

Sidenote: Error reporting should only be done in staging, and never production.

Footnotes:

To ensure that your field isn't empty, use empty().

• http://php.net/manual/en/function.empty.php

I.e.: if(!empty($_POST['field1-name'])){...}

The ! means "not", as in "if not empty".

The Problem

The real reason this script is failing to record anything into the database is because at line 7, you have a line of code that tells the script to die if there is an error in the database connection:

if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);

But what if the connection was successful? We look for the CLOSING BRACES for the if ($conn->connect_error) statement, which is found at line 22:

    }
?>

But instead of doing things that should happen if the connection is successful, this script ends immediately after the closing brace to the code block for the if ($conn->connect_error) statement. In other words, nothing happens.

The Fix

Remove the closing bracket at line 22, below the $conn->close(); statement; and place it instead immediately after the die(); statement.

Next, fix a few syntax errors:

1. You need a semicolon after the mysqli_real_escape_string() statement.
2. Don't use '-' (dashes or minus signs) in variable names. Remove them or replace them with the more conventional underscore character (_).

3. Your SQL syntax is incorrect. Try something like this:

   $sql = "INSERT INTO table_name ('APP_NAME') VALUES ('".$field1."')";

   Because you have already connected to your desired database ($dbname = "db";), SQL only needs to know the table to use within that database. Replace table_name from my example as appropriate. It'll be the table with a column called APP_NAME where it appears you want to store the form's post data. Finally, for the VALUES(), it is best to use the ('".$field1."') format rather than ('$field1') because it is more explicit. The latter will cause you problems under certain circumstances.

My rewrite of your code looks like this:

<?php
$servername = "xxx";
$username = "xxx";
$password = "xxx";
$dbname = "db";
$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
    $field1 =  mysqli_real_escape_string ( $conn , $_POST['field1']);

$sql = "INSERT INTO table_name ('APP_NAME') VALUES ('".$field1."')";

if ($conn->query($sql) === TRUE) {
    echo "OK";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();

?>