Set every username can choose the items in spinner one time - php

Question

My case now is every username can select the items in spinner one time only. Mean if the spinner has 5 item, the user can choose all of them but all of them just can one time only. Below are my select data php:
<?php
if($_SERVER['REQUEST_METHOD']=='POST'){
//Getting values
$username = $_POST['username'];
$name = $_POST['name'];
//Creating an sql query
$sql = "INSERT INTO Selection (username, name) VALUES
('$username','$name')";
//Importing our db connection script
require_once('dbConnect.php');
//Executing query to database
if(mysqli_query($con,$sql)){
echo 'Select Successfully';
}else{
echo 'Sorry, You Already Select it Before';
}
//Closing the database
mysqli_close($con);
}
The name in this php means the item in spinner. I am no idea how to set every username can select all the item in spinner one time only. I am using localhost phpmyadmin.

Answer 1

You can specify unique constraint for username and name columns.
Alter the Selection table using this code:
ALTER TABLE `Selection` ADD UNIQUE `unique_index`(`username`, `name`);
Now if you try to insert any username and name pair that is already inserted, will fail.

Answer 2

Why are you not testing if the entry is already on database before you do insert? May be this (Untested) code might help:
if($_SERVER['REQUEST_METHOD']=='POST')
{
//Getting values
$username = $_POST['username'];
$name = $_POST['name'];
//Importing our db connection script
require_once('dbConnect.php');
//Creating an sql query
$check_sql = "SELECT * FROM Selection WHERE username='$username' AND name='$name' LIMIT 1";
$check_res = $mysqli->query($con,$check_sql);
if($check_res && mysqli_num_rows($check_res) >0)
{
echo 'Sorry, You Already Select it Before';
}
else
{
$sql = "INSERT INTO Selection (username, name) VALUES ('$username','$name')";
if(mysqli_query($con,$sql))
{
echo 'Select Successfully';
}
else
{
echo "Select failed for some other reason";
}
}
//Closing the database
mysqli_close($con);
}

Answer 3

I think for checking the user to spin it only once only you need to add a flag in your database structure such as
u_id | flag |
--------------
1 | 1
--------------
So that when retrieving or fetching or you can say while checking you just have to make sure that this particular u_id has already spin it once so further it can't be allowed.
So before inserting check the username or user_id of particular.
$sql = "SELECT u_id from user_spins table where u_id = 1 AND flag = 1";
//if yes then don't allow to proceed
//if no then insert into User_spins table
$sql = "INSERT INTO User_spins (u_id, name,flag) VALUES
('$username','$name',1)";
//Importing our db connection script
require_once('dbConnect.php');