C# 如何循环表以更新每一行

我正在尝试使用instagramIds更新一列空值，这是我目前的方法，但console应用程序一直在运行，不更新数据库中的任何值

public static async Task<InstagramUser> ScrapeInstagram(string url)
{
    using (var client = new HttpClient())
    {
        var response = await client.GetAsync(url);
        if (response.IsSuccessStatusCode)
        {
            // create html document
            var htmlBody = await response.Content.ReadAsStringAsync();
            var htmlDocument = new HtmlDocument();
            htmlDocument.LoadHtml(htmlBody);

            // select script tags
            var scripts = htmlDocument.DocumentNode.SelectNodes("/html/body/script");

            // preprocess result
            var uselessString = "window._sharedData = ";
            var scriptInnerText = scripts[0].InnerText
                .Substring(uselessString.Length)
                .Replace(";", "");

            // serialize objects and fetch the user data
            dynamic jsonStuff = JObject.Parse(scriptInnerText);
            dynamic userProfile = jsonStuff["entry_data"]["ProfilePage"][0]["graphql"]["user"];

            List<String> columnData = new List<String>();


            //Update database query 
            string connectionString = @"Server=myProject-dev-db.cothtpanmcn7.ap-southeast-2.rds.amazonaws.com;Database=Projectdb;User Id=testadmin;Password=U8gs7vb7C7yvakXf;MultipleActiveResultSets=true;Trusted_Connection=False;";

            using (SqlConnection con = new SqlConnection(connectionString))
            {
                //get null values from database  
                string query = "Select * from ApplicationUser where InstagramId is null";
                using (SqlCommand command = new SqlCommand(query, con))
                {
                    command.Connection.Open();

                    using (SqlDataReader reader = command.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            columnData.Add(reader.GetString(0));
                        }
                    }
                }

                for (int index = 0; index < columnData.Count(); index++)
                {
                    //get username and scrape info 
                    var instagramInfo = new InstagramUser
                    {   
                        Id = userProfile.id,   
                    };
                    columnData.Add(instagramInfo.ToString());
                }

                SqlCommand cmd = new SqlCommand("Update ApplicationUser Set InstagramId = '" + columnData + "'" + "where InstagramUsername =  '" + userprofile.username + "'", con);
                cmd.Connection.Open();
                cmd.ExecuteNonQuery();

            }

            // create an InstagramUser
            var instagramUser = new InstagramUser
            {
                FullName = userProfile.full_name,
                FollowerCount = userProfile.edge_followed_by.count,
                FollowingCount = userProfile.edge_follow.count,
                Id = userProfile.id,
                url = url
            };
            return instagramUser;
        }
        else
        {
            throw new Exception($"Something wrong happened {response.StatusCode} - {response.ReasonPhrase} - {response.RequestMessage}");
        }
    }
}

我目前的做法是创建一个列表，将所有为空的Instagramid添加到该列表中。在删除Instagram中的用户名后，我将所有Instagramid添加到该列表中

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然后，我用instagram ID更新InstagramMuserName专栏，我不打算告诉您全部逻辑，只希望其中的一些步骤对您有效

使用istagramUserName的筛选器参数直接运行更新查询 e、 g更新表集IstagramID='123'，其中istagramUserName=OWAISSHAAB

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使用它是一个好主意。这将自动执行转换和转义序列。我正在尝试对数据库中的所有空值执行此操作，而不仅仅是一个值。好的，现在可以再启动一次1。以json格式2从api获取数据。使用serialization 3将其转换为c对象。在该对象上使用循环从数据库中逐行获取数据并进行更新，希望对您有所帮助