Learn Microsoft Access Advanced Programming Techniques, Tips and Tricks.

Saturday, December 25, 2010

GetRows Function and Exporting Data

Introduction

We are going to create a useful data export utility with the GetRows() method of the Recordset Object. The GetRows method is used for loading the entire set of data from the table into memory in a doubly dimensioned Variant Array with a single statement. Let us try it with an example to see how this is done. An image of a sample table is given below and we will see how this will look like in memory when loaded with the help of the GetRows() method of the Recordset Object:

Table: Employees
ID Name BirthDate Height Weight
1 Nancy 12/10/1980 164 58
2 Peter 05/07/1975 180 80
3 Linda 17/11/1982 170 60

The VBA Code.

The following sample VBA Routine loads the above data into memory and a listing is dumped in the Debug Window:

Public Function Test(ByVal tblName As String)
Dim db As Database, rst As Recordset, varData As Variant
Dim intFields As Integer, intRecords As Integer, j As Integer, k As Integer
Dim rec As String, fld_type As Integer

Set db = CurrentDb
Set rst = db.OpenRecordset(tblName, dbOpenTable)
j = rst.RecordCount - 1
k = rst.Fields.Count - 1

varData = rst.GetRows(j + 1)

For intRecords = 0 To j
    rec = ""
    For intFields = 0 To k
    fld_type = rst.Fields(intFields).Type

    If fld_type = 11 Or fld_type = 12 Then
      GoTo nextField
    End If
      rec = rec & varData(intFields, intRecords) & ","
nextField:
    Next
    rec = Left(rec, Len(rec) - 1)
    Debug.Print rec
Next
rst.Close
Set rst = Nothing
Set db = Nothing
End Function

The arrangement of records in memory in a two-dimensional array looks like the following:

1 2 3
Nancy Peter Linda
12/10/1980 05/07/1975 17/11/1982
164 180 170
58 80 60

The Memory Image of the Data.

The records are not arranged in row order as they appear in the datasheet view, they are loaded in columns instead.  So, after loading the data in memory we must know how to address the two-dimensional array to access each record in the correct order to output the data.  Each field value is separated with a comma in the listing provided in the Debug window.

Normally, in a two-dimensional array, the first index value of the array is the row number and the second one is the column number.  But, in this case, the first index value is the Field order Number and the second value is the Record Number.  You can check the sample data arrangement in the memory shown above.

Export Data in Text Format

We will write a small utility program to export any MS-Access Table into a comma-delimited Text/CSV File, so that the data can be easily transported through the internet or to import into other applications.

The VBA code of the program is given below:

Public Function CreateDelimited(ByVal xtableName As String, ByVal txtFilePath As String)
'-----------------------------------------------------
'Utility: CreateDelimited()
'Author : a.p.r.pillai
'Date   : Dec. 2010
'Purpose: Create Comma Delimited Text File from Table 
'Rights : All Rights Reserved by www.msaccesstips.com
'-----------------------------------------------------
Dim db As Database, rst As Recordset
Dim varTable() As Variant, j As Long, k As Long
Dim rec As String, fld_type As Integer
Dim intRecords As Integer, intFields As Integer

Set db = CurrentDb
Set rst = db.OpenRecordset(xtableName, dbOpenTable)
varTable = rst.GetRows(rst.RecordCount)
k = rst.Fields.Count - 1
j = rst.RecordCount - 1

Open txtFilePath For Output As #1
rec = ""
For intFields = 0 To k
   fld_type = rst.Fields(intFields).Type
        If fld_type = 11 Or fld_type = 12 Then GoTo nextField
   rec = rec & Chr$(34) & rst.Fields(intFields).Name & Chr$(34) & ","
nextField:
Next
rec = Left(rec, Len(rec) - 1)
Print #1, rec
For intRecords = 0 To j
    rec = ""
    For intFields = 0 To k
        fld_type = rst.Fields(intFields).Type
        If fld_type = 11 Or fld_type = 12 Then GoTo Next_Field
        rec = rec & IIf(fld_type = 10, Chr$(34) & varTable(intFields, intRecords) & Chr$(34), varTable(intFields, intRecords)) & ","
Next_Field:
        Next: rec = Left(rec, Len(rec) - 1)
        Print #1, rec
Next
Close #1
rst.Close

Set rst = Nothing
Set db = Nothing

End Function

The Utility can be called from a Command Button Click Event procedure after setting the Table name and the target file pathname in text boxes.  You can test the utility by calling it from the Debug Window (Immediate Window) directly as given below:

CreateDelimited "Products", "C:\Temp\Products.txt"

NB: If MEMO or Photo Fields are present in the Table they are excluded from the output file.

The target file extension can be either .TXT or .CSV.

Earlier Post Link References:

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