/// <summary>
    /// 返回一个数据
    /// </summary>
    /// <param name="strSql"></param>
    /// <returns></returns>
    public string ExecuteScalar(string strSql)
    {
        string tmp = "";
        SqlConnection conn = new SqlConnection(ConnectionString);
        try
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand(strSql, conn);
            tmp = cmd.ExecuteScalar().ToString();
            conn.Close();
        }
        catch { conn.Close(); }
        finally
        {
            conn.Close();
            conn.Dispose();//释放连接

        }
        return tmp;
    }
         //调用
        string sql3 = "select count(*) from fabiaoneirong"; 
        int count=Convert.Int32(ExecuteScalar(sql3));//行总数

------解决方案--------------------
int count=Convert.ToInt32(ExecuteScalar(sql3));//行总数
也可用int.Parse转换成整型，需注意下异常处理。

------解决方案--------------------
ds.Tables["aa"].Rows.Count