用 C# 构建嵌入式数据库引擎

Opening DbfDotNetDatabase: 185 ms
Insert 1000 individuals: 39 ms
Read individuals sequentially: 5 ms
Read individual randomly: 3 ms
Modifying individuals: 21 ms
Create DateOfBirth index: 77 ms
     Michael Simmons 22/07/1909
     Mark Adams 21/09/1909
     Charles Edwards 28/09/1909
     ... total 1000 records
Enumerate Individuals by age: 36 ms
Closing DbfDotNetDatabase: 44 ms

Opening ADO.Net Database: 459 ms
Insert 1000 individuals: 80601 ms
Read individuals sequentially: 1655 ms
Read individual randomly: 1666 ms
Modifying individuals: 75574 ms
Create DateOfBirth index: 80 ms
     Michael Simmons 22/07/1909
     Mark Adams 21/09/1909
     Charles Edwards 28/09/1909
     ... total 1000 records
Enumerate Individuals by age: 29 ms
Closing ADO.Net Database: 0 ms

DbfTable<dbfdotnetindividual> mIndividuals;

void CreateIndividualTable()
{
  mIndividuals = 
    new DbfTable<dbfdotnetindividual>(
      @"individuals.dbf", 
      Encoding.ASCII, 
      DbfDotNet.DbfVersion.dBaseIV);
}


class Individual
 : DbfDotNet.DbfRecord, IIndividual
 {
  [DbfDotNet.Column(Width = 20)]
  public string FIRSTNAME;
  [DbfDotNet.Column(Width = 20)]
  public string MIDDLENAME;
  [DbfDotNet.Column(Width = 20)]
  public string LASTNAME;
  public DateTime DOB;
  [DbfDotNet.Column(Width = 20)]
  public string STATE;
 }

Connection _cnn = null;


void ITestDatabase.CreateIndividualTable()
{
  _cnn = new System.Data.Connection(
"Data Source=adoNetTest.db");
  _cnn.Open();
  using (DbCommand cmd = _cnn.CreateCommand())
 {
   cmd.CommandText = "CREATE TABLE 
     INDIVIDUAL (ID int primary key, 
     FIRSTNAME VARCHAR(20), 
     MIDDLENAME VARCHAR(20), 
     LASTNAME VARCHAR(20), 
     DOB DATE, 
     STATE VARCHAR(20))";

    cmd.ExecuteNonQuery();
  }
}

void InsertNewIndividual(
   int id, 
   string firstname,
   string middlename,
   string lastname,
   DateTime dob,
   string state)
{
  var indiv = mIndividuals.NewRecord();
  indiv.FIRSTNAME = firstname;
  indiv.MIDDLENAME = middlename;
  indiv.LASTNAME = lastname;
  indiv.DOB = dob;
  indiv.STATE = state;
  indiv.SaveChanges();
}

void InsertNewIndividual(
  int id, 
  string firstname, 
  string middlename, 
  string lastname,
  DateTime dob, 
  string state)
{
 using (DbCommand cmd =
   _cnn.CreateCommand())
 {
  cmd.CommandText = string.Format(
   "INSERT INTO INDIVIDUAL (ID,
    FIRSTNAME, MIDDLENAME, LASTNAME, 
    DOB, STATE) VALUES({0},
    '{1}', '{2}', '{3}', 
    '{4}', '{5}');",
   id, firstname, middlename,
   lastname,
   dob.ToString("yyyy-MM-dd HH:mm:ss"),
   state);
  cmd.ExecuteNonQuery();
 }
}

IIndividual GetIndividualById(int id)
{
  DbfDotNetIndividual result =
    mIndividuals.GetRecord(id);
    return result;
}

IIndividual GetIndividualById(int id)
{
 using (DbCommand cmd =
   _cnn.CreateCommand())
 {
  cmd.CommandText = string.Format(
    "SELECT * FROM INDIVIDUAL
     WHERE ID=" + id);
  var reader = cmd.ExecuteReader();
  try
  {
   if (reader.Read())
    return GetNewIndividual(reader);
   else return null;
  }
  finally
  {
   reader.Close();
  }
 }
}

Individual GetNewIndividual(
DbDataReader reader)
{
 var res = new Individual();
 res.ID = reader.GetInt32(0);
 res.FirstName = reader.GetString(1); 
 res.MiddleName = reader.GetString(2);
 res.LastName = reader.GetString(3);
 res.Dob = reader.GetDateTime(4);
 res.State = reader.GetString(5);
 return res;
}

 class Individual : IIndividual
 {
  public int ID { get; set; }
  public string FirstName { get; set; }
  public string MiddleName { get; set; }
  public string LastName { get; set; }
  public DateTime Dob { get; set; }
  public string State { get; set; }
 }

void SaveIndividual(
  Individual individual)
{
  individual.SaveChanges();
}

void SaveIndividual(
  IIndividual individual)
{
 using (DbCommand cmd =
   _cnn.CreateCommand())
 {
  cmd.CommandText = string.Format(
    "UPDATE INDIVIDUAL
 SET DOB='{1}' WHERE ID={0};",
 individual.ID,
 individual.Dob.ToString(
   "yyyy-MM-dd HH:mm:ss"));
  cmd.ExecuteNonQuery();
 }
}