ASP Lecture 5: More ADODB

1
ASP Lecture 5 More ADODB

• Major objects Connection and Recordset
• Possible interfaces to a database
• via a connection (last lecture)
• directly (this week)

Recordset
Connection
DB
Recordset
Recordset
2
Comparison

• Connection
• Cleaner
• Allows multiple recordsets without recreating and
  duplicating the connection
• Easier to change in one place
• Just recordset
• Less code to write (not a good reason)

3
Using a connection

• Set DataConn Server.CreateObject("ADODB.Connecti
  on")
• strConnString "DRIVERMicrosoft Access Driver
  ...
• DataConn.Open strConnString, strUserId, strPasswd
• Set rsObj Server.CreateObject("ADODB.Recordset")
  
• cmdSQL SELECT
• rsObj.Open cmdSQL, DataConn, CursorType,
  LockType,..
• The first param is an SQL statement, a table,
  procedure name
• The second param is a connection object or string
  with connection text

4
Using a recordset

• With intermediate variables
• strConnString "DRIVERMicrosoft
  Access...
• Set rsObj Server.CreateObject("ADODB.Record
  set")
• rsObj.Open cmdSQL, strConnString,
• More confusing, put everything in the Open
  command
• rsObj.Open SELECT, "DRIVERMicrosoft
  Access,
• Examples of adding, deleting, updating an
  element .../samples/db_add.asp
  /samples/db_del.asp, .../samples/db_update.asp

5
ASP Components

• Components (e.g. ADODB) have classes
• e.g. Connection, Recordset, Field, Command,..
• Classes have methods
• e.g. Open, Close,..
• The ADODB.dll is available to ASP pages and
  supports this component
• An object is created in an ASP page with the
  create method of Server
• Server.CreateObject(component_name.class_name)
• objDataConn Server.CreateObject(ADODB.Connection
  )
• The object then has access to the methods of the
  class.

6
Developing components

• Most easily built in VB. Ref Shelly Powers.
• Open VB
• Select File/New Project/ActiveX DLL
• You get Project1 and a Class1 window
• Change Project1 name to Wells in
  Project/Properties
• Change Class1 name to CLA in the window for Class
  1
• Build functions for AddNew, Remove, in the
  (Code) window
• Public Function AddNew()
• ...
• End Function
• Make/Project creates Wells.dll
• regsvr32 Wells.dll registers it
• objCLA Server.CreateObject(Wells.CLA) creates
  an instance