Form Recordset and Bookmarks

Introduction.

Bookmarks are stored on the record of a Form's Recordset when the Form is loaded into memory.  When a Table or Query linked to a Form is open, a unique Id (of String Type) is generated and stored in the Bookmark Property of each record.  When you close the Form, the Bookmark Property value is cleared.  Bookmarks are two Byte data of String Type.  They are not displayable or printable characters, when printed on the screen, it simply displays a question mark symbol.

Not all Recordsets are Bookmarked and this can be checked by reading its 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 the third argument of the StrComp() 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 the same table a second time both session’s bookmarks of records will not be identical.

When a Linked Table having no Primary Key is open in a Form, then 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 Bookmark 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 the Northwind 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 its 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 a 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

The first three months of the year are the first quarter, the next three months belong to the second quarter, and so on.

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

For example: To prepare the 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 by the above-fixed pattern, then the task can be made easier by creating a small Function and using 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 a parameter. The Month() Function extracts the month number, from the date and uses it as a parameter for the Choose() Function to pick the correct Quarter Number from its 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 providing date as a parameter. When the date value passed to the function belongs to April, May, and June will return 2. These months belong to the Second Quarter of the Year. Dates for the next three months return 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 data filtering Query SQL is given below:

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

The GetQrtr() function extracts the Quarter numbers 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 set up 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 the report.

When Financial Year is from April to March next Year (Jan - Mar becomes the 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.

Earlier Post Link References:

• Custom Calculator and Eval Function
• Calculating Workdays From Date-Range
• Useful Report Function
• Calculating Time Difference

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