stop insert dublicate entery in my database - php

Question

we have use this below code to avoid to insert dublicate entery in our databse
but in some case it's not working
$device_id = $_REQUEST['device_id'];
$fcm_id = $_REQUEST['fcm_id'];
$model_number = $_REQUEST['model_number'];
$os_version = $_REQUEST['os_version'];
$app_version = $_REQUEST['app_version'];
$created = round(microtime(true) * 1000);
if(isset($device_id)){
$exist = mysqli_query($con, "SELECT * FROM `user` WHERE `device_id`='$device_id'");
if(mysqli_num_rows($exist)>0){
mysqli_query($con, "UPDATE `user` SET `fcm_id`='$fcm_id', `topics`=0 WHERE `device_id`='$device_id'");
}
else{
mysqli_query($con, "INSERT INTO `user` (`device_id`, `fcm_id`, `model_number`, `os_version`, `created`) VALUES ('".$device_id."', '".$fcm_id."', '".$model_number."', '".$os_version."', '".$created."')");
}

Answer 1

try with this
$device_id = $_REQUEST['device_id'];
$fcm_id = $_REQUEST['fcm_id'];
$model_number = $_REQUEST['model_number'];
$os_version = $_REQUEST['os_version'];
$app_version = $_REQUEST['app_version'];
$created = round(microtime(true) * 1000);
if(isset($device_id))
{
$qry="UPDATE `user` SET `fcm_id`='$fcm_id', `topics`=0 WHERE EXISTS (SELECT * FROM `user` WHERE `device_id`='$device_id')";
if(!mysqli_query($con,$qry)){ mysqli_query($con, "INSERT INTO `user` (`device_id`, `fcm_id`, `model_number`, `os_version`, `created`) VALUES ('".$device_id."', '".$fcm_id."', '".$model_number."', '".$os_version."', '".$created."')");
}

Answer 2

Try this
$device_id = $_REQUEST['device_id'];
$fcm_id = $_REQUEST['fcm_id'];
$model_number = $_REQUEST['model_number'];
$os_version = $_REQUEST['os_version'];
$app_version = $_REQUEST['app_version'];
$created = round(microtime(true) * 1000);
if(isset($device_id)){
$stmt = $con->prepare("INSERT IGNORE INTO `user` (`device_id`, `fcm_id`,
`model_number`, `os_version`, `created`) VALUES (?, ?, ?,?,?)");
$stmt->bind_param($device_id, $fcm_id, $model_number, $os_version, $created );
if ($stmt->execute()) {
}
$stmt->close();
}
Update: Add to your tabekl following index,
But you should think about what you put in the index.
because only when all 4 Columns are identical, no new entry will be crated.
CREATE UNIQUE INDEX idx_insert_user
ON user (`device_id`, `fcm_id`,
`model_number`, `os_version`);
the insert ignore into will not enter duplicates into the table

Answer 3

For stoping the duplicate data on row from mysql database on insert query:
MySQL INSERT IGNORE statement
For update case you need to put your condition for duplicate handling.