Access database accessing component (i)

access| Access | data | Database Access database accessing component (a) 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 ("<br><font color= #ff0000 >access_database_access:</ Font> "+e.message+" ("<br>");
}
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 to 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 ("<br><font color= #ff0000 >access_database_select: </font> "+tablename2+" <br>);

_tables[tablenametoindex (tableName2)]. Clear ();
Adapter. Fill (_tables[tablenametoindex (tableName2)]);

Adapter=null;
}
catch (Exception e)
{
System.Web.HttpContext.Current.Response.Write ("<br><font color= #ff0000 >access_database_select:</ Font> "+e.message+" ("<br>");
return false;
}
Finally
{
}
return true;
}


private bool Join (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 ("<br><font color= #ff0000 >access_database_select: </font> "+tablename2+" <br>);

_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 ("<br><font color= #ff0000 >access_database_join:</ Font> "+e.message+" ("<br>");
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 ("<br><font color= #ff0000 >access_database_view:</ Font> "+e.message+" ("<br>");
return false;
}
Finally
{
}
return true;
}



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



}
}