Learn Microsoft Access Advanced Programming Techniques, Tips and Tricks.

Form Recordset and Bookmarks

Introduction.

Bookmarks are stored on individual records of a Recordset, when loaded into memory on a Form.  When a Table or Query linked to a Form is open a unique Id is generated and stored in the Bookmark Property of each record.  When you close the Form this is cleared.  Bookmarks are a two Byte data of String Type.  They are not displayable or printable characters, when printed on screen it simply displays a ? character.

Not all Recordsets have Bookmarks and this can be checked by reading it’s  Bookmarkable Property Value.  If the Bookmarkable Property value is false then this Recordset doesn’t have bookmarks.

If you create a Recordsetclone in VBA from a Form’s (say Form-A) Recordset the Recordsetclone’s bookmark and Form’s Recordset bookmarks will be identical. You can use the StrComp() Function to compare Bookmarks.  Use 0 (zero) as third argument of the function.

But, if you load the same Table on a different Form (say Form-B) at the same time both form’s Recordset bookmarks will not be identical.  When you close and open the Form with same table a second time both session’s bookmarks of records will not be identical.

When an attached Table having no Primary Key is open in a Form that Recordset will not have any bookmarks.

When Form doesn’t have a Record Source Value then addressing Form’s Bookmark Property will trigger an error.  But, when a Table or Query is loaded into the Record Source property of the Form, the Form will have a Bookmark Property only for the Current Record.  You can move the records on the Form and read their bookmarks and save them into different Variables to come back to those records later through VBA.


Sample Bookmrk Based Trial Run.

Let us try a simple example to save the Bookmark of a record on the Form into a variable and use it later to come back to the bookmarked record.

  1. Import the Employees Table from Norwind sample database.
  2. Create a Tabular Form for Employees Table.
  3. On the Footer Section of the Form create two Command Buttons.
  4. Select the first Command Button.
  5. Display it’s Property Sheet (F4).
  6. Change the Name Property value to cmdSave. 
  7. Change the Name Property value of the second Command Button to cmdRestore.
  8. Display the VBA Module of the Employees Form.
  9. Copy and Paste the following Code into the VBA Module:
    Dim bkMark As Variant
    
    Private Sub cmdRestore_Click()
       Me.Bookmark = bkMark
       MsgBox "Bookmark Restored"
    End Sub
    
    Private Sub cmdSave_Click()
        bkMark = Me.Bookmark
        MsgBox "Bookmark saved" 
    End Sub
    
    
  10. Save and Close the Form.
  11. Open the Form in normal view showing employee records.
  12. Use the record navigation control to move to the 5th record.
  13. Click on the Save Command button to save the Bookmark of the current record in bkMark Variable.
  14. Now, move few records forward on the Form.
  15. Click on the Restore Command Button to quickly make the 5th record current on the Form, by copying the Bookmark from bkMark Variable into the Form’s Bookmark Property.  You can try this out with different records on the Form.

The following Links will show you more tricks on this topic with interesting examples:

  1. Form Bookmarks and Data Editing
  2. Form Bookmarks and Data Editing-2
  3. Form Bookmarks and Data Editing-3
  4. Forms and Custom Properties
  5. Saving Data on Forms not in Table
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Activity Dates and Quarterly Reports

Introduction.

There are four Quarters in a Year:

Jan - Mar = 1st Quarter
Apr - Jun = 2nd
Jul - Sep = 3rd
Oct - Dec = 4th

First three months of the year is first quarter, next three months belongs to second Quarter and so on.

Usually, when we prepare a Quarterly Report (for a period of three months based on the table above) we use date-range value to filter the required data for the report.

For example: To prepare Sales Report for the Second Quarter of Sales Year 2017 we will set the date range from April 1st, 2017 to June 30, 2017 as data filtering criteria in a SELECT Query. Probably we may use a Date-Picker control on the parameter entry Form to make it easier to pick and set the date values, rather than typing the date range manually.

If the Report preparation procedure is created on the above fixed pattern then the task can be made easier by creating a small Function and use it on the data filtering Query.


GetQrtr() Function Code.


Public Function GetQrtr(ByVal mPeriod As Date) As Integer

Dim mMonth As Integer

On Error GoTo GetQrtr_Err

mMonth = Month(Nz(mPeriod, 0))

If mMonth > 0 Then
    GetQrtr = Choose(mMonth, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4)
else
    GetQrtr = 0
End If

GetQrtr_Exit:
Exit Function

GetQrtr_Err:
GetQrtr = 0
Resume GetQrtr_Exit
End Function

The GetQrtr() Function takes the date value as parameter. The Month() Function extracts the month number from date and uses it as parameter for the Choose() Function to pick the correct Quarter Number from it's list.

When the month value is 1,2 or 3 the GetQrtr() function returns 1 to the calling procedure. The Function can be called from a Query, from other Functions, from Form control or from a Report Control by passing date as parameter. When date value passed to the function belongs to April, May, June will returns 2. These months belongs to the Second Quarter of the Year. Dates from next three months returns 3 and so on.


Using the Function in Query.

Let us see how we can use this Function in a Sales Query to extract data for Second Quarter 2017 Sales Report. Sample SQL of a data filtering Query is given below:


SELECT SALESTABLE.*
FROM SALESTABLE
WHERE (((SALESTABLE.SALESMANCODE="ABC") AND ((GetQrtr(([SALESDATE]))=2));


The GetQrtr() function extracts the Quarter number from all the Sales Record Dates, based on the Values we have lined up in the Choose() Function inside the GetQrtr() Function, compares them with the criteria parameter value 2 and filters the records for that period.


You may setup a Parameter Variable within the Query so that it will prompt for the criteria value, when the Query Runs, and can input the required value directly to filter the data for report.


When Financial Year is from April to March next Year (Jan - Mar become 4th quarter) still the filter criteria will be 1 to extract the data for the fourth quarter. The report heading Labels will indicate that the report is for the fourth quarter of Financial Year 2017-18.


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