Solved

ComboBox Value Lists Slow to Load

Posted on 2004-04-16
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Last Modified: 2012-06-27

I'm using Access 2002 with ADO and am using unbound forms and unbound comboboxes based on static lookup tables.  I'm designing it for frontend/backend use to later migrate to an .adp with perhaps SQL Server.  On the Form_Load event, I populate the combo boxes based on static lookup lists by setting their RowSource properties to a string with the semicolon delimited value list.  This works fine, except when the number of rows becomes somewhat large, and then it takes one to two seconds for that particular combobox to load.  It's also slow to scroll.  Rather annoying.  

As an example, I have a Countries lookup table with three fields (RecordID, CountryName, and TelCode) with 238 rows.  The code fundamentally looks something like this snippet (though the string is built differently from the simple example below):

strRows = "1;Afghanistan;930;2;Albania;355;"      ' string goes on for all countries
cboCntry.ColumnCount = 3
cboCntry.ColumnWidths = "0;2000;0"
cboCntry.BoundColumn = 0
cboCntry.LimitToList = True
cboCntry.AutoExpand = False
cboCntry.AutoExpand = False
cboCntry.RowSourceType = "Value List"
cboCntry.RowSource = strRows

1)  Is the slowness in loading and scrolling long value lists in fact typical behavior for a combobox using a RowSourceType = "Value List"?

2)  If yes, then a thought I've had is to set the RowSourceType = "Table/Query" and set the RowSources  to respective local tables or queries in a separate front-end mdb holding nothing but static lookup tables.   Does that make sense?  If so, how would I create a separate ADO connection to it for the comboboxes' RowSource property?

Thanks,
Wyatt
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Question by:WyattRidesAgain
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12 Comments
 
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Expert Comment

by:Lou Dufresne
ID: 10845776
Hi Wyatt,
    This is a wild guess. Add an index(s) to the table or combo box list. This may make it run faster.

Lou
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Expert Comment

by:stevbe
ID: 10845862
go with your second thought, store the data in a local table.

You can use the currentproject.connection as the connection object for the recordset you are using for the combobox
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Author Comment

by:WyattRidesAgain
ID: 10845934
Hi Stevbe,

Can I use a recordset as the combo box rowsource?  I don't mean by looping through its records to either build the rowsource string or to use .AddItems one record at at time, which I understand.  Rather, I mean can you directly set the rowsource equal to the recordset, like you would with a table or query source?  I tried doing that (setting the recordset) and I got a 'type mismatch' error.

Wyatt
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Expert Comment

by:stevbe
ID: 10845989
I don't have my reference material here with me but ... yes, you can set the source of a combobox to be a recordset. I think that you can only do this with an ADO recordset, what object library are you using to build your recordset with?

Steve
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Accepted Solution

by:
stevbe earned 250 total points
ID: 10846032
yup ... just set it up and tested fine.

Steve

Option Compare Database
Option Explicit


Dim mrst As ADODB.Recordset

Private Sub Form_Open(Cancel As Integer)
    Set mrst = New ADODB.Recordset
    mrst.Open Source:="SELECT * FROM tblContact", _
              ActiveConnection:=CurrentProject.Connection, _
              CursorType:=adOpenKeyset, _
              LockType:=adLockOptimistic
    Set Me.cboADO.Recordset = mrst
End Sub
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Author Comment

by:WyattRidesAgain
ID: 10846035

That's encouraging.  I'm using ADO 2.7 library.  Can you send a quick n dirty code snippet to illustrate?  I'm guessing I have the wrong combinations of combo box properties that rejects the recordset.

Wyatt
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Author Comment

by:WyattRidesAgain
ID: 10846044

Ooops.  I replied before I saw the code.  Sorry.  Lemme give it a try.

Wyatt
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Expert Comment

by:stevbe
ID: 10846096
not that it will make much of a difference but you can set the locktype to readonly which will speed things up a hair.

  LockType:=adLockReadOnly


the real key is the cursortype being set to keyset which is also what you need to do when binding a form's recordset to an in memory recordset.

Steve
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Author Comment

by:WyattRidesAgain
ID: 10846173

Steve,

It works great!!!!  Fast and clean.  Perfect.

I didn't know to look for the recordset property for the combo box object.  Learned something good today.

Many thanks!  Points are coming.
Wyatt
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Expert Comment

by:stevbe
ID: 10846262
You are welcome, glad I could help.

Steve
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Expert Comment

by:JonoB
ID: 11201314
Well, this is exactly what I have been trying to do for a while, but I am still struggling.

Any idea of what ADO library you need for this to work?

I am using A2000, with the Microsoft ADO 2.6 library and I get a "Method or data member not found" error on the me.cboADO.Recordset line.

Any suggestions?

Thanks for the help.
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LVL 39

Expert Comment

by:stevbe
ID: 11205500
This is a closed question, you should open your own. The method we used to solve this question will not work in Access 2000.

Steve
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