How To Create a Custom Text File Import Routine

This article provides a framework for a custom text import routine using low-level file I/O to read files, string parsing, and DAO to store the data.

When importing delimited text files, the Jet Text ISAM driver truncates leading spaces on fields not surrounded by quotes or other text qualifiers, and truncates trailing spaces on all fields regardless of whether quotes are used to qualify the data.

If you need leading and/or trailing spaces to be preserved or need to read the data in a situation where Jet's Text ISAM driver cannot be used, you will need a custom import routine.

The following code is a template you can use to build a custom import routine.

WARNING: Your use or modification of the CODE provided in this article is at your own risk. Microsoft provides this CODE "as is" without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. Microsoft does not support modifications of the CODE to suit specific customer requirements.

Sample Code:

1. Using Notepad, create a text file with the following data:
   
   1, Description 1 ,1,100.00,3/1/1998
   2, Description 2 ,2,200.00,3/2/1998
2. Save the file as c:\test.txt.
3. In Visual Basic, create a new project and add a reference for Microsoft DAO 3.5 Object Library. In Access, open the Northwind.MDB database.
4. Create a new form with a CommandButton (Command1) and the following code:

         Private Sub Command1_Click ()
         Dim F As Long, sLine As String, A(0 To 4) As String
         Dim db As Database, rs As Recordset
           F = FreeFile
           Open "c:\test.txt" For Input As F
          ' uncomment following line if you want to skip field headings
          ' Line Input #F, sLine
           Set db = CurrentDb                               ' Access only
           Set db = DBEngine(0).OpenDatabase("biblio.mdb")  ' Visual Basic
           On Error Resume Next
           db.Execute "DROP TABLE TestImport"
           On Error Goto 0
           db.Execute "CREATE TABLE TestImport (ID LONG, [Desc] TEXT (50), " _
                     & "Qty LONG, Cost CURRENCY, OrdDate DATETIME)"
           Set rs = db.OpenRecordset("TestImport", dbOpenTable)
           Do While Not EOF(F)
             Line Input #F, sLine
             ParseToArray sLine, A()
             rs.AddNew
             rs(0) = Val(A(0))
             rs(1) = A(1)
             rs(2) = Val(A(2))
             rs(3) = Val(A(3))
             rs(4) = CDate(A(4))
             rs.Update
           Loop
           rs.Close
           db.Close
           Close #F
         End Sub
   
         Sub ParseToArray(sLine As String, A() As String)
         Dim P As Long, LastPos As Long, I As Long
           P = InStr(sLine, ",")
           Do While P
             A(I) = Mid$(sLine, LastPos + 1, P - LastPos - 1)
             LastPos = P
             I = I + 1
             P = InStr(LastPos + 1, sLine, ",", vbBinaryCompare)
           Loop
           A(I) = Mid$(sLine, LastPos + 1)
         End Sub
   
   					

5. Run the project/form and click the CommandButton to import the data.
6. Examine the contents of the TestImport table and note that the Desc column has both leading and trailing spaces preserved and that other fields have been correctly converted to the appropriate data type.
   
   NOTE: In Visual Basic, you can use the VISDATA sample project to examine the contents of the table.