Mysql c# Mysql.Data.Mysqlclient.MysqlException (0x80004005): Unknown column 'lotete' in 'field list'

Ok so i have error 'Mysql.Data.Mysqlclient.MysqlException (0x80004005): Unknown column 'lotete' in 'field list' when im trying to insert a new value

C# code

string sql = "INSERT INTO `users` (`username`,`email`,`password`, `key`) VALUES (`lotete`, `test`, `xd`, `test2`)";
    if (connection != null)
    {
        connection.Open();
        MySqlCommand command = connection.CreateCommand();
        command.CommandText = sql;
        try
        {
            //command.Parameters.AddWithValue("@username", userName);
            command.ExecuteNonQuery();
        }
        catch (System.Exception ex)
        {
            Debug.LogError("MySQL error: " + ex.ToString());
        }
    }

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You should use Parameters for command to prevent SQL Injection.

command.CommandText = "INSERT INTO users(username,email,password, key) VALUES(@username, @email, @password, @key)";
command.Parameters.AddWithValue("@username", "lotete");
command.Parameters.AddWithValue("@email", "test@test.com");
command.Parameters.AddWithValue("@password", "testtest");
command.Parameters.AddWithValue("@key", "test2");