在特定值之后插入一行 - C#

Question

我有一个查询，它提供超过 500 行，我根据特定列（例如名称）对它们进行了排序，并且我正在将结果写入文本文件中。 我想在每组的最后一行之后添加一个中断记录。 比如我的查询结果是：

Name Address City State Zip   Phone   Break
AAA  BBB     CCC   SS   1234  555     
AAA  DDD     EEE   SS   1234  666
MMM  YYY     ZZZ   EE   4457  999
LLL  DDD     ooo   WW   7895  777

但我想添加一个额外的行并在文本文件中添加“是”作为中断值：

Name Address City State Zip   Phone   Break
AAA  BBB     CCC   SS   1234  555     
AAA  DDD     EEE   SS   1234  666
                                       YES
MMM  YYY     ZZZ   EE   4457  999
                                       YES
LLL  DDD     ooo   WW   7895  777
                                       YES

我的代码是：

string query = " select * from table order by name";
SqlDataReader reader;
string connStr = ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
string strDelimiter = "\t";
string strDel = "\"";
string strFilePath = @"C:\" TextFile_" + DateTime.Now.ToString("yyyyMMdd") + ".txt";
StringBuilder sb = new StringBuilder();

using (SqlConnection conn = new SqlConnection(connStr))
{
    conn.Open();
    using (reader = new SqlCommand(query, conn).ExecuteReader())
    {

        for (int i = 0; i < reader.FieldCount; i++)
        {
            sb.Append(strDel);
            sb.Append(reader.GetName(i));
            sb.Append(strDel);
            if (i == reader.FieldCount - 1)
            {
                continue;
            }
            sb.Append(strDelimiter);
        }
        sb.Append(Environment.NewLine);
        if (reader.HasRows)
        {
            Object[] items = new Object[reader.FieldCount];

            while (reader.Read())
            {
                reader.GetValues(items);
                for (int i = 0; i < reader.FieldCount; i++)
                {
                    sb.Append(strDel);
                    sb.Append(reader.GetValue(i).ToString());
                    sb.Append(strDel);
                    if (i == reader.FieldCount - 1)
                    {
                        continue;
                    }
                    sb.Append(strDelimiter);
                }
                sb.Append(Environment.NewLine);

            }
        }
    }
    conn.Close();
    File.WriteAllText(strFilePath, sb.ToString());
}

Answer 1

var breakLine = new List<YourType> { new YourType { Break = "Yes"}};

var result = collection.GroupBy(item => item.Name)
                       .SelectMany(grouping => grouping.Union(breakLine))
                       .ToList();