我尝试从表中获取行数：

        string commandLine = "SELECT COUNT(*) FROM client";

        using (MysqLConnection connect = new MysqLConnection(connectionStringMysqL))
        using (MysqLCommand cmd = new MysqLCommand(commandLine,connect))
        {
            connect.Open();

            int count = (int)cmd.ExecuteScalar();

            return count;
        }

我得到了例外：

Specified cast is not valid.

知道我怎么解决它？