我混合了sql和sqli命令..但这会给出错误..正确的代码是什么？ [重复]

Question

This question already has an answer here:

• When to use single quotes, double quotes, and backticks in MySQL 12 answers

There's some error in this piece of code..can someone care to correct me?

$user_list=mysqli_query("SELECT 'id','username', FROM 'users' ");
    while($run_user=mysqli_fetch_array($user_list)){
        $user=$run_user['id'];
        $username=$run_user['username'];
        echo "<p><a href='send.php?user=$user'>$username</a></p>";
        }

From comments made below -

mysqli_query() expects at least 2 parameters, 1 given in D:\wamp\www\2\send.php on line 44

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Answer 1

Just replace quotes with backtick also mysqli_query need connection in your first parameter

 $user_list=mysqli_query(PASS_YOUR_CONNECTION_VARIABLE,"SELECT `id`,`username` FROM `users`");