我正在从MySQL数据库文件中提取数据，并将其中的三个数据项加载到称为索引的方法中，该方法提取“名称”，“姓氏”和“电话号码”字段.....主要目标是按字母顺序加载所有数据按姓氏字母排列，如果两个姓氏匹配，则应按字母顺序对它们进行排序。
using Data_Layer;
using System.Collections.Generic;
using System.Data;
using System.Linq;
namespace Business_Logic_Layer
{
public class BusinessLogic
{
public List<PhoneIndex> phoneIndex = new List<PhoneIndex>();
public void createPhoneIndex()
{
string tableName = "customers";
DataConnection dc = new DataConnection();
DataSet customers = dc.selectData(tableName);
foreach (DataRow customer_row in customers.Tables[0].Rows)
{
string surname, name, telephone;
surname = name = telephone = "";
for (int i = 0; i < customers.Tables[0].Columns.Count; i++)
{
if (customers.Tables[0].Columns[i].ColumnName.StartsWith("contactFirstName"))
{
name = customer_row.ItemArray[i].ToString();
}
else if (customers.Tables[0].Columns[i].ColumnName.StartsWith("contactLastName"))
{
surname = customer_row.ItemArray[i].ToString();
}
else if (customers.Tables[0].Columns[i].ColumnName.StartsWith("phone"))
{
telephone = customer_row.ItemArray[i].ToString();
}
}
// Add the information to the main phoneIndex
bool added = false;
PhoneIndexEntry temp_index_entry = new PhoneIndexEntry() { name = name, surname = surname, telephone = telephone };
for (int i = 0; i < phoneIndex.Count; i++)
{
if (surname.StartsWith(phoneIndex[i].letter))
{
phoneIndex[i].entries.Add(temp_index_entry);
added = true;
}
}
if (!added)
{
PhoneIndex temp_index = new PhoneIndex() { letter = surname.Substring(0, 1), entries = new List<PhoneIndexEntry>() { temp_index_entry } };
phoneIndex.Add(temp_index);
added = true;
}
}
} // End of method createPhoneIndex()
public void sortPhoneIndex()
{
// Your code goes here...
string surname, name;
surname = name = "";
List<PhoneIndex> phoneIndex = new List<PhoneIndex>() { };
PhoneIndexEntry temp_index_entry = new PhoneIndexEntry() { name = name, surname = surname };
foreach (PhoneIndex index in phoneIndex)//letter, entries sort through letters
{
string[] sortedLetter = new string[1];
for (int i = 0; i < phoneIndex.Count - 1; i++)
{
for (int j = i + 1; j < phoneIndex.Count; j++)
{
if (phoneIndex[i].letter.CompareTo(phoneIndex[j].letter) > 0)
{
sortedLetter[0] = phoneIndex[i].letter;
phoneIndex[i].letter = phoneIndex[j].letter;
phoneIndex[j].letter = sortedLetter[0];
}
}
}
//if name==name compare surname for sorting
return;
}
}//end of foreach
} // End of method sortPhoneIndex()
} // End of Class BusinessLogic
public class PhoneIndex
{
public string letter { get; set; }
public List<PhoneIndexEntry> entries { get; set; }
} // End of Class PhoneIndex
public class PhoneIndexEntry
{
public string name { get; set; }
public string surname { get; set; }
public string telephone { get; set; }
} // End of Class PhoneIndexEntry
// End of Namespace Business_Logic_Layer
A =
安东尼，亚当斯，0670510248
B = 比尔亚当斯0724677987 比尔，坩埚，0687944987
答案 0 :(得分：0)
假设您无法更改从数据库中检索数据的方式，那么Linq可以轻松完成此工作。
// Example data .....
DataTable dt = new DataTable();
dt.Columns.Add("name", typeof(string));
dt.Columns.Add("surname", typeof(string));
dt.Columns.Add("phone", typeof(string));
dt.Rows.Add("charles", "dickens", "11232");
dt.Rows.Add("mark", "twain", "453446");
dt.Rows.Add("howard", "lovecraft", "875564");
dt.Rows.Add("ernst", "hemingway", "1647567");
dt.Rows.Add("thomas", "mann", "56434");
dt.Rows.Add("isaac", "asimov", "9700");
dt.Rows.Add("aldous", "huxley", "2654");
List<PhoneIndex> phoneIndex = new List<PhoneIndex>();
// Let's enumerate the datatable grouping by first letter in the surname column
var names = dt.AsEnumerable().GroupBy(d => d.Field<string>("surname").Substring(0, 1))
// foreach group build a sublist with the info from the datarow
// transformed in a PhoneIndexEntry.
.Select(g => g.Select(p => new PhoneIndexEntry
{
name = p.Field<string>("name"),
surname = p.Field<string>("surname"),
telephone = p.Field<string>("phone")
}));
// Now we have an IEnumerable<IEnumerable> where the first enumerable is a list
// of all distinct first letter from the surname column, while the second
// is an enumerable of PhoneIndexEntry.
// We can loop over the first Enumerable ordering it
// by the first surname's letter and creating a PhoneIndex with all the PhoneIndexEntry for that specific letter
foreach (var entry in names.OrderBy(n => n.First().surname[0].ToString()))
phoneIndex.Add(new PhoneIndex { letter = entry.First().surname[0].ToString(), entries = entry.OrderBy(s => s.surname).ToList()});
旁注：看来您有一个非常糟糕的 do_it_all 方法（SelectData），该方法在其中传递表名并从该表中取回所有数据。
当然，这不是查询数据库的好方法，除非您检索的记录很少，否则建议您为每次数据提取编写特定的方法，或者花一些时间来学习如何使用ORM库。