The MySQL query does not return a value, but exists in DB

I have a funky problem.. I have this code:

using (MySqlCommand cmd = new MySqlCommand())
{
    cmd.Connection = this.connection;
    cmd.CommandText = "SELECT id FROM links WHERE url LIKE '@url'";
    cmd.Parameters.AddWithValue("@url", parent_url.Trim());
    cmd.Prepare();

    using (MySqlDataReader reader = cmd.ExecuteReader())
    {
        while (reader.Read())
        {
            parent_id = reader.GetInt32(0);
        }
    }
}

What my problem is that.. sometimes it doesn't return a value when there is a an answer in the database. That's very strange. Also I have noticed that some items in the database have a space behind it so this is why I made this:

    using (MySqlCommand cmd = new MySqlCommand())
    {
        cmd.Connection = this.connection;
        cmd.CommandText = "SELECT id FROM links WHERE url LIKE '@url'";
        cmd.Parameters.AddWithValue("@url", parent_url.Trim());
        cmd.Prepare();

        using (MySqlDataReader reader = cmd.ExecuteReader())
        {
            while (reader.Read())
            {
                parent_id = reader.GetInt32(0);
            }
        }
    }

    if(parent_id == 0)
    {
        using (MySqlCommand cmd = new MySqlCommand())
        {
            cmd.Connection = this.connection;
            cmd.CommandText = "SELECT id FROM links WHERE url LIKE '@url '";
            cmd.Parameters.AddWithValue("@url", parent_url.Trim());
            cmd.Prepare();

            using (MySqlDataReader reader = cmd.ExecuteReader())
            {
                while (reader.Read())
                {
                    parent_id = reader.GetInt32(0);
                }
            }
        }
    }

But it still doesn't help me some times.. even if the item doesn't have a space after it. So yea.. can you guys please give me some advice.. what should I try.

---

"SELECT id FROM links WHERE url LIKE @url";

remove the '' from the parameter then only it will consider as parameter

otherwise it will be only a string value equal to @url

and also if you need to search given string on database column use % like below

cmd.Parameters.AddWithValue("@url", "%" + parent_url.Trim()+ "%");

UPDATE:

you can use trim function as below

"SELECT id FROM links WHERE trim(url) LIKE @url";