DAO Vs ADO (Database Management)

DAO vs ADO - The latest viewpoints.

DAO or ADO? Which should I use? This is a commonly asked question, especially in view of the changing development paths that Microsoft has taken over the last few years. Which is best for your application? The answer may not be as straightforward as you may think!


Let’s start by defining a few things:

DAO - Data Access Objects
Allows VB applications to talk to a database (the JET Engine) via ODBC. DAO was Microsoft's first object oriented solution for the manipulation of databases using the Jet Database Engine.

ADO - ActiveX Data Objects
Allows VB/Other Web Tools (Browsers) to interface with different kinds of data sources. ADO is a more recent Microsoft Data Access technology.

ACEDAO - Access Engine Data Access Objects
Allows VB applications to talk to a database (the Access Database Engine). ACEDAO is Microsoft’s enhanced version of DAO, built specifically for working with the new ACE database engine in Access 2007.

Is newer always better?

In the early days of Microsoft Access the choice was simple. DAO was the only option. It was built to talk easily and efficiently with the built-in Jet Engine of an Access application. Since Access 2000, things started to get a little murky, as ADO was packaged as the default object model. Why did Microsoft change their paradigm? As newer technologies developed, ADO was seen as the preferred method to connect to disparate sources (SQL Server, Oracle, XML, etc.).

In order to fully utilize all the rich features of these newer sources ADO has more things going on “under the hood”. This tends to slow some things down if all you need are the basics. If you are dealing solely with an Access (Jet) database, then DAO will perform faster than ADO and should be your tool of choice for your application. If you are using Access as a front-end for connecting to another source that can benefit from the newer ADO features, then ADO is for you.

Listed below are some pros and cons for each. This should not be considered as an exhaustive list.

DAO Pros:

* Fast
* Stable, bug-free code
* Integrates well with Access (Jet) databases.
* Shares the Access connection. Does not open a separate connection to the database when running in Access.


DAO Cons:

* Does not scale well to other databases
* Does not scale well to large recordsets (million+ record queries with lots of business logic can take a long time)
* Has a very deep object model requiring a lot of "." notation
* Does not scale well to web interfaces
* Does not support disconnected recordsets


ADO Pros:

* Scales to virtually all databases that run on a MS platform
* Runs quickly on large recordsets. (DAO can sometimes outperform ADO in that it does not load the entire recordset when first called, but rather loads records incrementally, only as necessary. ADO will yield faster results with functions performed on the entire large recordset.)
* Works great with tables in Access that are really connections to tables or views in other types of databases
* Has some nice methods that DAO doesn't for testing status of recordset
* Has a very shallow object model (basically Connection Command And Recordset)
* Supports disconnected recordsets
* Supports stateless HTTP protocols
* Providers are also available for non-MS platforms such as AS/400
* Supports ANSI-92 DDL query statements such as GRANT + REVOKE statements.
* Can apply Sort and Filter properties 'in place'. Does not require a separate Recordset object to use Sort and Filter.


ADO Cons:

* Slightly slower than DAO
* Does not really work with Access 97 and previous versions
* Syntax is more difficult for beginners
* Requires second library for some data definition activities (ADOX)


Some more things to consider. Since Access 2003, DAO has returned to be the default library in Access. This includes Access 2007. The ADO library is no longer referenced when creating a new .MDB or .ACCDB in A2007. In Access 2007 Microsoft has included more features in DAO (ACEDAO) to allow you to work with the new features of the enhanced database engine (.ACCDB). Most notably, these features are:

Multi-value lookup fields
A multi-value lookup field is a field that can store multiple related values for a given record in an embedded recordset.

Attachment fields
The database engine supports a new data type called Attachment that can be used to store files in a database. The files are compressed for storage unless the file being added is already compressed. There is also a new Attachment control in Access 2007 to support this data type.

Append only memo fields
Memo fields support a new property called AppendOnly that is used to track column history for data changes to the field. Each change made to an append only field is saved in the database and can be retrieved using a new method on the Access.Application object called ColumnHistory.

Conclusion:

DAO is not going anywhere. Microsoft is committed to supporting it well into the future. If your application is purely a Microsoft Access database, then DAO should be the obvious choice. If you need some advanced recordset manipulation features and are connecting to a supportive outside source, then ADO is the ticket. Also, it should be noted that there is nothing wrong with mixing these two methods within the same project.

Source: UtterAccess.com
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Synchronize Outlook, Google Calendar, Gmail, IPod and Mobile phone

This is a guide for synchronizing Contacts (address book) and Calendars (schedule) across multiple computers and gadgets. This is one of the articles which I had bookmarked for more than a year and hence, may not necessarily be the best solution today.

Common Terms:

• synchronization - making the information the same on two different applications
• WAP/GPRS - wireless Internet access for mobile phones
• SyncML - a synchronization protocol

This is the setup I am trying to sync:

• Calendars
  
  • Microsoft Outlook at work for professional scheduling
  
  
  • Google Calendar for personal scheduling
  
  
• Contacts
  
  • Gmail for email addresses
  
  
  • Microsoft Outlook at home for contacts
  
  
• Gadgets
  
  • Nokia 6682
    for access to contacts/calendar on the go (or any mobile phone that has
    software to synchronize with Microsoft Outlook, ie: all of them)
  
  
  • iPod for access to contacts/calendar on the go
    

ScheduleWorld wasn’t something I used before I tried to do this, but it is the glue that holds it all together.

Here is a beautiful drawing of The Plan. It was made with Gliffy, a web-based Visio clone.

This is how I want to sync it (follow the diagram):

• Contacts are sourced from my Phone + Outlook (at home).
• Calendar is sourced from Outlook (at work), Google Calendar, ScheduleWorld.
• I only want to synchronize my phone/iPod when I’m at home (so I don’t have to bring the USB cables back and forth)
• I don’t want to synchronize over WAP/GPRS (wireless data) because I am a cheap. My local wireless provider charges too much.

It should be easy to extend these instructions to your specific

situation. If this isn’t your boat I also list some alternatives at the
end of the article. If you have a specific question, post a comment and
I’ll try to answer it. Sometimes the owner of ScheduleWorld pops by and
gives suggestions as well.

But why?

1. Why use Outlook? Isn’t Microsoft “Outbreak” the devil?
   
   • I won’t be using Outlook for email. Outlook is a necessary evil if
     you want to do contacts synchronization since it is the only software
     that you mobile phone supports synching with.
   • ScheduleWorld also supports Evolution/Linux and Thunderbird/Windows.
   
   
2. What about Linux/Mac OS X support?
   
   • Microsoft Outlook is fundamental to how I’m moving the data from my computer to my phone/iPod.
   • You can replace Microsoft Outlook with Evolution or Thunderbird and still use it with ScheduleWorld.
   
   
3. Why not source contacts from Gmail?
   
   • You can’t automatically sync Gmail to anything.
   • If you have a free solution for synching Gmail to Outlook then please post a comment.
   • Gmail also adds any you’ve emailed to your address book automatically. Gets cumbersome.
   
   
4. Why use ScheduleWorld?
   
   • It’s there. It’s free. It automatically supports Google Calendar synching.
   • The interface for ScheduleWorld looks like PHP iCalendar. You could run your own Funambol
     server instead, but it wouldn’t be as slick. No, Funambol isn’t a
     clever name for a new hemorrhoid cream. ScheduleWorld uses the Funambol
     server for SyncML interoperability and that’s it.
   • ScheduleWorld is quite a large project and does a number of things outside of SyncML.
   
   
5. Why don’t you sync email?
   
   • I like using computers for email. My thumb gets sore.
   • The approach I’ve outlined doesn’t sync email. I’d recommend using Mobile Gmail with a data plan to access mail on your phone and on any computer.
   
   
6. Why don’t you use Remote Calendars and cut ScheduleWorld out of the loop altogether?
   
   • I tried Remote Calendars and I found it a bit of a pain. It
     requires three other Microsoft tools installed (.NET, Office Something,
     VSO). It would still give me “Invalid URI” errors even though it was
     synching properly. Screw that. The Funambol Outlook plug-in is simple.
   
   

#1. Synching Phone to Outlook

I used a fresh install of Microsoft Outlook. I chose not to
associate it with an email address or import data from Microsoft
Outlook Express. You could use an existing install.

Connect phone to PC.

1. (Optional) Use Nokia/phone supplied software to BACKUP existing phone contacts.
2. Use the Nokia/phone supplied PC Suite synchronization software to
   sync existing phone contacts to Outlook (also synching Calendar, Notes,
   To-do).

#2. Synching Gmail to Outlook (at home)

There are several solutions out there, but I recommend manually
updating by downloading your Gmail contacts to a CSV file and then
importing it into Outlook. More information on CSV files here.

1. Login to Gmail and export contacts:
   
   • 
     

     Contacts >> All Contacts >> Export >> Outlook CSV >> Export Contacts

     
     
   
   
2. (Optional) I recommend loading it into Excel and hand-merging the
   contacts with the contacts you copied from your phone. Delete all the
   hand-merged and unnecessary contacts and THEN import the pared down CSV
   file into Outlook.This really is the best way. Every one of your
   friends has three different email addresses. You have to hand-merge
   them, and no program is going to do it for you (properly). It goes
   faster than you might think.
3. Import the merged contacts into Outlook:
   
   • 
     

     File >> Import from another program or file
     >> CSV (Windows) >> [Browse] >> Next >>
     [Contacts] >> Next >> Finish

     
     
   
   
4. (Optional) Now comes the fun part. Sift through the Outlook
   Contacts list a few times and make sure the data is correct. Now is the
   time to remove duplicates, before they’re synched everywhere else. That
   person from the bar that time? Probably don’t need that number.
5. Go take a break and have some cookies and a glass of milk. Watch
   something on TV. I think America’s Next Top Model is on. Then sift
   through the address book again.
6. (Optional) BACK UP THE OUTLOOK CONTACTS! You won’t be doing
   anything with them, but if something screws up this could be an
   essential recovery point.
   
   • 
     

     File >> Export >> CSV (Windows) >>
     Next >> Contacts >> Next >> outlook-backup.csv
     >> Next >> Finish.

     
     

#3. Synching Google Calendar to ScheduleWorld

1. Log in to ScheduleWorld and click on Preferences.
2. Scroll down to the Calendar Preferences.
3. Enter your Gmail account name that is used with your Google Calendar.
4. Click “Grant Access” to allow ScheduleWorld to connect to your Google Calendar.
   
   • ScheduleWorld is in the process of registering with Google
     (2006/09/19), so by the time you try this there won’t be the same
     yellow warning text.
   
   
5. You will be taken back to the ScheduleWorld Preferences page.
   
   • 
   
   
6. Click on the “Automatically sync with your specific Google Calendar…” checkbox.
7. Click on the “Find Calendars” button, wait, and then select the calendar you want to sync from the drop down box.
8. Click on the “Test URL” to make sure you can access the Google Calendar.
9. Click “Save” to save your calendar Preferences.
10. Under “Standard SyncML Client Configuration”, take note of your
    ScheduleWorld server url, username, and password. Save it in notepad.
    
    • 
    
    
11. Click on the supported clients link: http://www.scheduleworld.com/tg/syncmlInfo.jsp
12. Download the Outlook client.
13. NOTE: I had trouble getting the Funambol iPod synchronizer working, so we’ll use a different method (iTunes).

#4. Synchronizing Outlook (at work) to ScheduleWorld

1. Close Outlook and install the Funambol Outlook plug-in at http://www.scheduleworld.com/tg/syncmlInfo.jsp
2. Run the plug-in.
   
   • 
     

     Start >> All Programs >> Funambol >> Outlook Plug-in >> Funambol Outlook Plug-in

     
     
   
   
3. Input configuration settings for ScheduleWorld.
   
   • 
     

     Configuration >> Edit >> Communication Settings >> [Input ScheduleWorld url, userid and password]

     
     
   
   
4. At work I want to push the calendar to ScheduleWorld (one way sync) and I don’t want to sync contacts. You may want to do something else, like use File >> Recover (slow sync) for two-way synchronization.
   
   • 
     

     Configuration >> Edit >> Synchronization
     Settings >> [unclick Contacts] >> [Calendar: Update remote
     data]

     
     
   
   
5. Click Synchronize and wait
   
   • .
   
   
6. Set up automatic synchronization.
   
   • 
     

     Configuration >> Edit >> Scheduler Settings
     >> [Click activate] >> [Set the time period, I chose 12
     hours]

     
     
   
   

I set up my Outlook at work to synchronize automatically every day at 5pm/5am (before my home syncs).

#5. Synchronizing Outlook (at home) to ScheduleWorld

1. Close Outlook and install the Funambol Outlook plug-in at http://www.scheduleworld.com/tg/syncmlInfo.jsp
2. Run the plug-in.
   
   • 
     

     Start >> All Programs >> Funambol >> Outlook Plug-in >> Funambol Outlook Plug-in

     
     
   
   
3. Input configuration settings for ScheduleWorld.
   
   • 
     

     Configuration >> Edit >> Communication Settings >> [Input ScheduleWorld url, userid and password]

     
     
   
   
4. At home I want to push the contacts (one way sync) and pull the calendar (one way sync). You may want to do something else, like use File >> Recover (slow sync) for two-way synchronization.
   
   • 
     

     Configuration >> Edit >> Synchronization
     Settings >> [Contacts: Replace remote data] >> [Calendar:
     Replace local data]

     
     
   
   
5. Click Synchronize and wait. A while. Got any more milk and cookies?
   
   • 
   
   
6. Set up automatic synchronization.
   
   • 
     

     Configuration >> Edit >> Scheduler Settings
     >> [Click activate] >> [Set the time period, I chose 12
     hours]

     
     
   
   

I set up my Outlook at home to synchronize automatically every day at 6pm/6am (after my work syncs).

#6. Synchronizing Gmail with ScheduleWorld

The Gmail / ScheduleWorld synchronization isn’t automatic, but it does
allow you to push your contacts from ScheduleWorld to Gmail. Instead of
exporting from ScheduleWorld, you could simple export from Outlook (at
home) to Gmail as documented here.

I like using the ScheduleWorld approach because it will only
synchronize contacts with email addresses. You can also use
ScheduleWorld as an LDAP server for Gmail.

1. Log in to ScheduleWorld:
   
   • 
     

     Contacts >> Utils >> Download Contacts in Google Format >> [Save GoogleImportContacts.csv]

     
     
   
   
2. Log in to Gmail.
3. (Optional) Delete existing Gmail contacts.
   
   • 
     

     Contacts >> All Contacts >> Select All >> Delete

     
     
   
   
4. Import contacts.
   
   • 
     

     Contacts >> Import >> [Browse to GoogleImportContacts.csv]

     
     
   
   

#7. Synchronizing iPod with Microsoft Outlook using iTunes

• Connect iPod.
• Open Outlook.
• Open iTunes.
  
  • 
    

    Edit >> Preferences >> iPod >>
    Contacts >> Synchronize contacts from: Microsoft Outlook >>
    Calendars >> Synchronize calendars from Microsoft Outlook
    >> Ok

    
    
  
  
• Go to Outlook and look for “A program is trying to access” dialog box and choose “Allow access for 10 minutes” / “Yes”
• Wait, but not very long.

Your Microsoft Outlook contacts/calendars will be synced whenever you connect your iPod and run iTunes.

Known Issues:

• This is a Windows solution that requires Microsoft Outlook, but
  that is only because Outlook is the only thing supported by my Nokia
  6682 cellphone.
  
  • ScheduleWorld supports Thunderbird/Evolution.
  
  
• Manually synching your phone to your computer via Bluetooth / cable
  is pointless if you have a flat GPRS data rate. I don’t. You can
  directly sync your phone to ScheduleWorld over GRPS, and skip a bunch
  of steps.
• Gmail synchronization is manual, not automatic.
• ScheduleWorld only supports synching to (1) Google Calendar (but there are plans to support more).
• This solution is dependant on ScheduleWorld.
• May need Microsoft Office opened before autosync to iPod using iTunes.

Source: The Holy Grail of Synchronization (internetducttape.com)

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