Question

环顾四周，无法弄清楚如何做到这一点。

我试图查询数据表。我在第一列搜索字符串值，我需要在第二列中返回与其对应的整数。

当我有这个整数时，我需要将1加到整数值并用更新的信息编辑行。

 public static string hashtag_counter(string message)
    {
        int hashcounter = 0;
        DataTable hashtags = new DataTable();
        DataRow row = new DataRow();
        hashtags.Columns.Add("Hashtag", typeof(string));
        hashtags.Columns.Add("Count", typeof(int));


        string[] words = message.Split(' ');
        foreach (string word in words)
        {
            if (word.StartsWith("#"))
            {
                if (hashtags.Columns.Contains(word))
                {
                    DataRow[] selection = hashtags.Select("Hashtag == " + word);

                }
            }
            else
            {
                row = hashtags.NewRow();
                row["Hashtag"] = word;
                row["Count"] = "1";
                hashtags.Rows.Add(row);
            }

我似乎无法在任何地方找到这个，所以任何帮助都会受到赞赏

Answer 1

如果我遵循您问题中的要求，那么您的代码应该是这样的。

.....
string[] words = message.Split(' ');

// Execute the loop ONLY for the required words (the ones that starts with #)
foreach (string word in words.Where(x => x.StartsWith("#")))
{
    // Search if the table contains a row with the current word in the Hashtag column
    DataRow[] selection = hashtags.Select("Hashtag = '" + word + "'");
    if(selection.Length > 0)
    {
        // We have a row with that term. Increment the counter
        // Notice that selection is an array of DataRows (albeit with just one element)
        // so we need to select the first row [0], second column [1] for the value to update
        int count = Convert.ToInt32(selection[0][1]) + 1;
        selection[0][1] = count;
    }
    else
    {
        row = hashtags.NewRow();
        row["Hashtag"] = word;
        row["Count"] = "1";
        hashtags.Rows.Add(row);
    }

}

请注意，如果您想在字符串字段上选择，那么您需要在搜索字词周围使用引号，而不需要在C＃中使用==喜欢

根据查询结果编辑DataTable

1 个答案: