MySQL affected rows -1 when inserting data into database - php

Question

I want to create a simple piece of code that will put data into the database form a PHP script, everything works fine except putting the data into the database! (I am running a server with PHP7)
The output of the affected rows shows -1 (strange), I double checked my code, compared it with others, tried searching for a common issue on the internet, even tried on a local server with no avail.
You can see it here:
https://leer.bosvision.nl/register.php
My code:
<?php
$conn = mysqli_connect("localhost", "-user-", "-pass-", "-db-");
if(!$conn) {
$msg = die('connection error');
} else {
$msg = 'Connection success.';
}
echo $msg;
?>
<?php
$query = 'INSERT INTO users_two (ID, username, password) VALUES (1, gfd, gfd)';
if(mysqli_query($conn, $query)) {
$result = 'Data saved';
} else {
$result = 'No data saved';
}
$affected = mysqli_affected_rows($conn);
echo $result . '.' . ' Affected rows: ' . $affected;
?>

Answer 1

To quote the documentation:
-1 indicates that the query returned an error.
And your insert statement indeed errors out, since you don't have a gfd column. If you meant to use that as a value, it should be surrounded by single quotes:
$query = "INSERT INTO users_two (ID, username, password) VALUES (1, 'gfd', 'gfd')";
# Here -------------------------------------------------------------^---^--^---^

Answer 2

<?php
$conn = mysqli_connect("localhost", "-user-", "-pass-", "-db-");
if(!$conn) {
$msg = die('connection error');
} else {
$msg = 'Connection success.';
}
echo $msg;
?>
<?php
$query = "INSERT INTO users_two (username, password) VALUES ('gfd', 'gfd')";
if($result= mysqli_query($conn, $query)) {
$result = 'Data saved';
} else {
$result = 'No data saved';
}
$affected = mysqli_affected_rows($conn);
echo $result . '.' . ' Affected rows: ' . $affected;
?>
One assumes ID is auto increment, so that doesn't need to be in there, or is it not and the issue you are encountering is that its a duplicate entry for key. Also you need to wrap your var data in ' '
I would guess that this is an SQL issue. Can you run your query directly on your database? That would give you the error.

Answer 3

Read this page for more info: PHP insert statement
$sql = "INSERT INTO MyGuests (firstname, lastname, email) VALUES ('John', 'Doe', 'john#example.com')";
if ($conn->query($sql) === TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
Normally you shouldn't be inserting an ID yourself because it should be auto increment.

Answer 4

try adding quotes to the string values, as in:
"INSERT INTO users_two (ID, username, password) VALUES (1, 'gfd', 'gfd')"