Select, Insert and Update MySQL table PHP script not working - php

Question

I wrote the following code:
<?php
$servername = "domain";
$insert = 12345678;
$username = "user";
$password = "password";
$dbname = "database";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT quantity FROM Eshop WHERE id = $insert";
$result = $conn->query($sql);
echo $result;
if ($result > 0) {
$result = $result + 1;
$sql2 = "UPDATE Eshop SET quantity = $result WHERE id = $insert";
if ($conn->query($sql2) === TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $sql2 . "<br>" . $conn->error;
}
} else {
$sql3 = "INSERT INTO Eshop (id, quantity) VALUES ($insert, 1)";
if ($conn->query($sql3) === TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $sql3 . "<br>" . $conn->error;
}
}
?>
What I want this script to do is select the quantity where the id is $insert and then if quantity > 0, add 1 to the quantity and update the quantity, if not insert the id and quantity = 1 into the table. The table has only two fields id(VARCHAR(32)) and quantity(DECIMAL(8,1)). I tried to do it more general in order to help as many people as possible. Could you please help me? Thanks in advance. NOTE: When I run the script in the browser(after uploading it to the server with the correct username,domain etc.) nothing shows up and I dont even get an error in the console.

Answer 1

You need to extract the result of your query and loop through each row:
<?php
$servername = "domain";
$insert = 12345678;
$username = "user";
$password = "password";
$dbname = "database";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT quantity FROM Eshop WHERE id = $insert";
$result = $conn->query($sql);
while($row = mysqli_fetch_array($result)) {
if ($row['quantity'] > 0) {
$new_quantity = $row['quantity'] + 1;
$sql2 = "UPDATE Eshop SET quantity = '$new_quantity' WHERE id = '$insert'";
if ($conn->query($sql2) == TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $sql2 . "<br>" . $conn->error;
}
} else {
$sql3 = "INSERT INTO Eshop (id, quantity) VALUES ('$insert', 1)";
if ($conn->query($sql3) == TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $sql3 . "<br>" . $conn->error;
}
}
}
?>

Answer 2

<?php
$servername = "domain";
$insert = 12345678;
$username = "user";
$password = "password";
$dbname = "database";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT quantity FROM Eshop WHERE id = $insert";
$result = $conn->query($sql);
//check if particular record exists or not
$count=mysql_num_rows($result);
if($count>0) // if records exists for the particular id
{
while($row = mysqli_fetch_array($result)) {
if ($row['quantity'] > 0) {
$new_quantity = $row['quantity'] + 1;
$update = "UPDATE Eshop SET quantity = '$new_quantity' WHERE id = '$insert'";
if ($conn->query($update ) == TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $update . "<br>" . $conn->error;
}
} else {
$insert = "INSERT INTO Eshop (id, quantity) VALUES ('$insert', 1)";
if ($conn->query($insert ) === TRUE) {
echo "New record created successfully";
} else {
echo "Error: " . $insert . "<br>" . $conn->error;
}
} // else qty is <=0
} //end while
}
else {
echo "Records do not exists for that particular id";
}
?>