Comparing AbsolutePosition to PercentPosition in VB 4.0

• Professional and Enterprise Editions of Microsoft Visual Basic, version 4.0, for Windows

SUMMARY

In Microsoft Visual Basic 4.0 using Jet's DAO model, there are two Properties that can help you determine the current cursor position or that you can use to set the cursor to a certain position.

This article will demonstrate both properties and give you some ideas on when to use one or the other.

MORE INFORMATION

According information from the online Help, the description of the AbsolutePosition is as follows:

Returns or sets the relative record number of a Recordset object's current record. Applies to the Recordset Object as a Dynaset-type or Snapshot- type(except for forward-only Snapshots and passthrough queries).

According information from the online Help, the description of the PercentPosition is as follows:

Returns or sets a value that indicates or changes the approximate location of the current record in the Recordset object based on a percentage of the records in the Recordset. Applies to all three types of Recordset Objects (except for forward-only Snapshots and passthrough queries).

In the following code, I use the rs.MoveLast method before referring to rs.PercentPosition. This is because PercentPosition is dependent on RecordCount, and AbsolutePosition is not. The RecordCount property is not accurate until you move to the end of your Recordset object. Also keep in mind that RecordCount is not always 100 percent accurate, it is just an estimate of the number of rows in your recordset, and therefore PercentPosition is not always accurate--but AbsolutePosition is always accurate. For instance, a dynaset in a multi-user environment does not reflect rows other users have added until you issue the refresh method.

Step-by-Step Example

1. Start Visual Basic or from the File menu, choose New Project (ALT, F, N) if Visual Basic is already running. Form1 is created by default.

2. Add two Command buttons(Command1, Command2), four Labels (Label1, Label2, Label3, Label4), one Data Control(Data1) and one Text box(Text1) to Form1. Place Label1 to the left of Text1 and place Label2 next to the Data control. Place Label3 next to the Command1 button and place Label4 next to the Command2 button.

3. Set the following properties for each control:

      Default   Property        Set to
      -----------------------------------------------
      Command1   Caption        AbsolutePosition
      Command2   Caption        PercentPosition
      Data1      DatabaseName   BIBLIO.MDB
      Data1      RecordSource   Titles
      Label1     Caption        Enter a Number:
      Text1      Text
      Label2     Caption
      Label2     DataSource     Data1
      Label2     DataField      Title
      Label3     Caption
      Label4     Caption
   
   

4. Add the following code to the Command1_Click event:

      Private Sub Command1_Click()
        Dim rs1 As Recordset
        Set rs1 = Data1.Recordset
        rs1.MoveLast
        rs1.AbsolutePosition = Val(Text1.Text)
        Label3.Caption = "Absolute Results: " & rs1("title")
      End Sub
   
   

5. Add the following code to the Command2_Click event:

      Private Sub Command2_Click()
        Dim rs2 As Recordset
        Set rs2 = Data1.Recordset
        rs2.MoveLast    'RecordCount now accurate
        rs2.PercentPosition = Val(Text1.Text)
        Label4.Caption = "Percent Results: " & rs2("title")
      End Sub
   
   

6. From the Run menu, choose Start (ALT, R, S), or press the F5 key to run the program. Enter a number from 1 to 100 into Text1. Press the Command1 button, then press the Command2 button. Look at the different results in Label3 versus Label4. You can test the location by selecting the arrow keys of the Data control also.

   You can experiment with different numbers to get different results. The PercentPosition property is good for helping in displaying a status bar type of indicator. The AbsolutePosition property could be used as a reference for jumping to certain records, but you could use a BookMark as well.