string ww = "今天发工资心情不错!";
        for (int i = 0; i <= ww.Length - 1; i++)
        {
            for (int j = 1; j <= ww.Length - i ; j++)
            {
                string A = ww.Substring(i, j);
            }
        }
感觉数据库里的like就是这么做的