.NET开发：ACCESS数据库访问组件（一）

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ACCESS数据库访问组件（一）

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ACCESS数据库访问组件（一）ACCESS_Database.cs

using System;
using System.Data;
using System.Data.OleDb;
using System.Collections;

namespace XLang.VideoOnline.Framework.Database.Access
{
/// <summary>
/// XLang.VideoOnline.Framework.Database is designed for create, update, insert and delete operations.
/// </summary>

public class Access
{
private OleDbConnection _connection;

private string _connectionString;

private string _databaseName;

private Database.Access.DataTablesCollection _tables;

private Database.Access.DataViewsCollection _views;

private DateTime _creationTime;

private DateTime _lastAccessTime;

private DateTime _lastWriteTime;

  public string Name
  {
   get
   {
    return _databaseName;
   }
  }

  public Database.Access.DataTablesCollection Tables
  {
   get
   {
    return _tables;
   }
  }

  public Database.Access.DataViewsCollection Views
  {
   get
   {
    return _views;
   }
  }

  public DateTime CreationTime
  {
   get
   {
    return _creationTime;
   }
  }

  public DateTime LastAccessTime
  {
   get
   {
    return _lastAccessTime;
   }
  }

  public DateTime LastWriteTime
  {
   get
   {
    return _lastWriteTime;
   }
  }

  public Access()
  {
  }

public Access(string databaseName)
{

   string delimStr = " :\\./";
   char [] delimiter = delimStr.ToCharArray();
   string [] split = null;
   split=databaseName.Split(delimiter);

   _databaseName = split[split.Length-2];
   _connectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source="+databaseName;
   _creationTime = System.IO.File.GetCreationTime(databaseName);
   _lastAccessTime = System.IO.File.GetLastAccessTime(databaseName);
   _lastWriteTime = System.IO.File.GetLastWriteTime(databaseName);
   _connection = new OleDbConnection( _connectionString );

   try
   {
    if(!(_connection.State==ConnectionState.Open)) _connection.Open();

_tables=new Database.Access.DataTablesCollection(_connection);
 _views=new DataViewsCollection(_connection);
 }
 catch(Exception e)
 {
 System.Web.HttpContext.Current.Response.Write(" ACCESS_Database_Access:"+e.Message+" ");
 }
 finally
 {
 if(_connection.State==ConnectionState.Open) _connection.Close();
 }
 }

  public bool ExecuteCommand(string commandString,CommandType commandType)
  {

   switch(commandType)
   {
    case CommandType.Create:
     return Create(commandString);
    case CommandType.Delete:
     return Delete(commandString);
    case CommandType.Insert:
     return Insert(commandString);
    case CommandType.Select:
     return Select(commandString);
    case CommandType.Join:
     return Join(commandString);
    case CommandType.Update:
     return Update(commandString);
    case CommandType.View:
     return View(commandString);
    case CommandType.Other:
     return Other(commandString);
    default:
     break;
   }
   return true;
  }

  private bool Create(string commandString)
  {
   return CreateDeleteInsertUpdate(commandString);
  }

  private bool Delete(string commandString)
  {
   return CreateDeleteInsertUpdate(commandString);
  }

  private bool Insert(string commandString)
  {
   return CreateDeleteInsertUpdate(commandString);
  }

  private bool Select(string commandString)
  {
   try
   {
    OleDbDataAdapter adapter=new OleDbDataAdapter(commandString,_connection);

//    string tableName=null;
//    string delimStr = " ";
//    char [] delimiter = delimStr.ToCharArray();
//    string [] split = null;
//    split=commandString.Split(delimiter);
//    tableName=split[4].Trim();

string from="FROM";
 int fromIndex=commandString.IndexOf(from);
 string subCommandString=commandString.Substring(fromIndex+4).Trim();
 int endIndex=subCommandString.IndexOf(' ');
 string tableName2=null;
 if(endIndex<0)
 tableName2=subCommandString.Substring(0).Trim();
 else
 tableName2=subCommandString.Substring(0,endIndex).Trim();
 //System.Web.HttpContext.Current.Response.Write(" ACCESS_Database_Select:"+tableName2+" ");

_tables[TableNameToIndex(tableName2)].Clear();
adapter.Fill(_tables[TableNameToIndex(tableName2)]);

adapter=null;
 }
 catch(Exception e)
 {
 System.Web.HttpContext.Current.Response.Write(" ACCESS_Database_Select:"+e.Message+" ");
 return false;
 }
 finally
 {
 }
 return true;
 }

  private bool Join(string commandString)
  {
   try
   {
    OleDbDataAdapter adapter=new OleDbDataAdapter(commandString,_connection);

// string from="FROM";
// int fromIndex=commandString.IndexOf(from);
// string subCommandString=commandString.Substring(fromIndex+4).Trim();
// int endIndex=subCommandString.IndexOf(' ');
// string tableName2=null;
// if(endIndex<0)
// tableName2=subCommandString.Substring(0).Trim();
// else
// tableName2=subCommandString.Substring(0,endIndex).Trim();
 //System.Web.HttpContext.Current.Response.Write(" ACCESS_Database_Select:"+tableName2+" ");

//    _tables[TableNameToIndex(tableName2)].Clear();
//    adapter.Fill(_tables[TableNameToIndex(tableName2)]);
//    if(_tables["temp"]!=null)
//     _tables[TableNameToIndex("temp")].Clear();
//    else
//    {
//     _tables[_tables.Count]=new Database.Access.DataTable("temp");
//     _tables[TableNameToIndex("temp")].Clear();
//    }

_tables[TableNameToIndex("temp")].Clear();
adapter.Fill(_tables[TableNameToIndex("temp")]);

adapter=null;
 }
 catch(Exception e)
 {
 System.Web.HttpContext.Current.Response.Write(" ACCESS_Database_Join:"+e.Message+" ");
 return false;
 }
 finally
 {
 }
 return true;
 }

private int TableNameToIndex(string tableName)
 {
 for(int i=0;i<_tables.Count;i++)
 {
 if(_tables[i].Name.ToUpper()==tableName.ToUpper())
 return i;
 }
 return -1;
 }

private int ViewNameToIndex(string viewName)
 {
 for(int i=0;i<_tables.Count;i++)
 {
 if(_views[i].Name.ToUpper()==viewName.ToUpper())
 return i;
 }
 return -1;
 }

  private bool Update(string commandString)
  {
   return CreateDeleteInsertUpdate(commandString);
  }

  private bool CreateDeleteInsertUpdate(string commandString)
  {
   if(!(_connection.State==ConnectionState.Open)) _connection.Open();
   // Start a local transaction.
   OleDbTransaction myTrans =_connection.BeginTransaction();

   // Enlist the command in the current transaction.
   OleDbCommand myCommand = _connection.CreateCommand();
   myCommand.Transaction = myTrans;

   try
   {
    myCommand.CommandText = commandString;
    myCommand.ExecuteNonQuery();
    myTrans.Commit();
   }
   catch(Exception e)
   {
    try
    {
     myTrans.Rollback();
    }
    catch (OleDbException ex)
    {
     if (myTrans.Connection != null)
     {
      //Console.WriteLine("An exception of type " + ex.GetType() +
      // " was encountered while attempting to roll back the transaction.");
     }
    }
    return false;
   }
   finally
   {
    if(_connection.State==ConnectionState.Open) _connection.Close();
   }

return true;
}

private bool View(string commandString)
 {
 try
 {
 string from="FROM";
 int fromIndex=commandString.IndexOf(from);
 string subCommandString=commandString.Substring(fromIndex+4).Trim();
 int endIndex=subCommandString.IndexOf(' ');
 string viewName=null;
 if(endIndex<0)
 viewName=subCommandString.Substring(0).Trim();
 else
 viewName=subCommandString.Substring(0,endIndex).Trim();

OleDbDataAdapter adapter=new OleDbDataAdapter(commandString,_connection);

_views[ViewNameToIndex(viewName)].Clear();
adapter.Fill(_views[ViewNameToIndex(viewName)]);

adapter=null;
 }
 catch(Exception e)
 {
 System.Web.HttpContext.Current.Response.Write(" ACCESS_Database_View:"+e.Message+" ");
 return false;
 }
 finally
 {
 }
 return true;
 }

  private bool Other(string commandString)
  {
   return true;
  }

}
}

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