需要向此文件和if语句添加count（*）

Question

When I change SELECT * to SELECT count(*) the script stops working altogether. How to I add a count(*) to this file and a statement if row count for $user >= 20 allow to INSERT else do nothing.

// Include needed files

include 'mysql.php';

// Connect to MySQL

connectMySQL();

//****** SECURITY CHECK *********

session_start();
if(isset($_SESSION['userid'])){
$user = mysql_real_escape_string($_SESSION['userid']); 

//*******************************

  // Retrieves variables through AJAX

$favid = mysql_real_escape_string($_GET['favid']);
// $favid = mysql_real_escape_string($_GET['favid']);

// Firstly, check if article is favourite or not

$query = mysql_query("SELECT * FROM ajaxfavourites WHERE user='$user' AND  favid='$favid'");
$matches = mysql_num_rows($query);

// If it is not favourited, add as favourite

if($matches == '0'){
mysql_query("INSERT INTO ajaxfavourites (user, favid, exptime) VALUES ('$user', '$favid', CURRENT_TIMESTAMP)");

echo "";
}


// Instead, if it is favourited, then remove from favourites

if($matches != '0'){
mysql_query("DELETE FROM ajaxfavourites WHERE user='$user' AND favid='$favid'");

echo "";
}

} else {

// Someone tries to directly access the file!

echo "Invalid session!";

}

Thanks!

Answer 1

try to use below query, using below query if requested user's session will be 20+ then only insert statement will execute else insert statement will be ignore.

INSERT INTO ajaxfavourites(USER,favid ,exptime)  
SELECT  1 AS USER, 1 AS favid, NOW() AS exptime
FROM ajaxfavourites WHERE USER=1  HAVING COUNT(*) >=20;