I have these tables and i want to get news from News table, but the news that have been added after the user had logged in & he didn't see the data Depending on the Query that is shown in the PHP script.
The Users When they are logging in to the system they register their Login Time-stamp. After a while a service asks the server about the new data for that User_ID and check the seen table if the news is not in the seen table and the Current Time-stamp is Greater than the logged in Time-stamp then the news is new.
Users Table
User_ID | User_Name |User_Login
-------------------------------
1 | John |2016-04-13 16:01:12
2 | Carl |2016-04-13 16:13:22
3 | Tomas |2016-04-13 16:01:01
4 | Adam |2016-04-13 16:04:44
5 | Nancy |2016-04-13 16:04:37
News Table
News_ID | News_Text | News_Post_TimeStamp
----------------------------------------------
1 | Hello World | 2016-04-13 16:09:23
2 | This is My car | 2016-04-13 16:10:24
3 | I had Ate pizza| 2016-04-13 16:11:40
4 | Leave Me Alone | 2016-04-13 16:15:30
5 | C++ Programming| 2016-04-13 16:09:50
Seen Table
ID | User_Id | News_Id
---------------------------
1 | 1 | 2
2 | 1 | 3
3 | 4 | 1
4 | 5 | 3
5 | 1 | 4
UPDATE This is my PHP Script Code:
<?php
require('config.php');
$conn = mysqli_connect($servername, $username, $password, $db);
$query="SELECT * FROM news,users WHERE news.news_id NOT IN (SELECT news_id FROM seen WHERE user_id = '".$_GET['id']."') AND users.user_login<Now() ";
$result = mysqli_query($conn,$query);
$rows = array();
echo mysqli_error($conn);
while($row = mysqli_fetch_assoc($result)) {
$rows[] = $row;
}
echo json_encode($rows);
?>
and This is the JSON Format:
[{"News_id":"1","News_Text":"C++programming","news_post_timestamp":"2016- 04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"1","News_Text":"C++programming","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"2","News_Text":"Pizza","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"2","News_Text":"Pizza","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"3","News_Text":"Android","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"3","News_Text":"Android","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"4","News_Text":"Ahmad","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"4","News_Text":"Ahmad","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"5","News_Text":"Toto","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"5","News_Text":"Toto","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"6","News_Text":"JaVA","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"6","News_Text":"JaVA","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"7","News_Text":"Computer","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"7","News_Text":"Computer","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"8","News_Text":"Test","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"8","News_Text":"Test","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"9","News_Text":"Test","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"9","News_Text":"Test","news_post_timestamp":"2016-04-13 16:09:41","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"},{"News_id":"10","News_Text":"Al Hasasd","news_post_timestamp":"2016-04-13 16:47:44","User_Id":"14","User_Name":"John","user_login":"2016-04-13 16:04:37"},{"News_id":"10","News_Text":"Al Hasasd","news_post_timestamp":"2016-04-13 16:47:44","User_Id":"15","User_Name":"Carl","user_login":"2016-04-13 16:04:37"}]
There is a duplicate in the Results , if anyone can tell me how to remove duplicate ?
Your SQL should be this (exemple with User_ID 1)
SELECT *
FROM news n
WHERE news_id NOT IN (SELECT news_id FROM news_seen WHERE user_id = 1)
AND News_Post_TimeStamp > (SELECT User_Login FROM user_table WHERE User_ID = 1)
(adapt user_table accordingly)
But prior to simply do this, you should adapt your PHP code because what you are doing is an invitation to a SQL injection.
Ideally you should use parameterized queries.
But, assuming your USER_ID is CHAR type as you had quotes in your query, you can just make your code a bit safer using this simple sanitize function that I added to your code.
<?php
require('config.php');
$conn = mysqli_connect($servername, $username, $password, $db);
$userid = sanitize($_GET['id']);
$query="SELECT * FROM news WHERE news_id NOT IN (SELECT news_id FROM news_seen WHERE user_id = '$userid') AND News_Post_TimeStamp > (SELECT User_Login FROM user_table WHERE User_ID = '$userid')";
$result = mysqli_query($conn,$query);
$rows = array();
echo mysqli_error($conn);
while($row = mysqli_fetch_assoc($result)) {
$rows[] = $row;
}
echo json_encode($rows);
function sanitize($data)
{
// remove whitespaces (not a must though)
$data = trim($data);
// apply stripslashes if magic_quotes_gpc is enabled
if(get_magic_quotes_gpc())
{
$data = stripslashes($data);
}
// a mySQL connection is required before using this function
$data = mysql_real_escape_string($data);
return $data;
}
?>