Rocky Smolin
rockysmolin at bchacc.com
Thu Feb 28 23:15:23 CST 2013
I thought I remember trying to do this and you can't - you have to re-create
the field. But here's a snip from a thread I found:
************************************************************************
You can't change the size of an existing field without generating an
error, AFAIK. You can, however, create a temp field of the right size,
copy data over, delete the old one, create the new one, copy the data
over (to preserve field names), and delete the temp field. Any indexes
or relationships will generate and error, however.
Sub FieldChange()
'This will fail if the field is a part of any index or
relationship.....
'Additional code is needed if that is a possibility
Dim dbs As DAO.Database
Dim tdf As DAO.TableDef
Dim fld As DAO.Field
Set dbs = CurrentDb
Set tdf = dbs.TableDefs("Contacts")
Set fld = tdf.CreateField("LastName1", dbText, 255)
tdf.Fields.Append fld
dbs.Execute "Update Contacts set lastname1 = lastname"
tdf.Fields.Delete "LastName"
tdf.Fields.Refresh
Set fld = tdf.CreateField("LastName", dbText, 255)
tdf.Fields.Append fld
dbs.Execute "Update Contacts set lastname = lastname1"
tdf.Fields.Delete "LastName1"
tdf.Fields.Refresh
Set fld = Nothing
Set tdf = Nothing
Set dbs = Nothing
End Sub
************************************************************************
Shorter than the code from the link below but doesn't take care of
re-creating the indezes.
HTH
Rocky
-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of John Bodin
Sent: Thursday, February 28, 2013 8:17 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] changing Field Size programmatically
Hi Steve,
Used this code in an A2010 app, worked real well. It is free, according to
the web-site. Here's the link and the code for just the modify field size
routine. Good luck.
http://aislebyaisle.com/access/vba_backend_code.htm
'
' Free Code from http://aislebyaisle.com/access/vba_backend_code.htm
'
'---------------------------------------------------------------------------
-----
'
' MSysObjects TYPES:
' 1 = Tables
' 6 = Attached Tables
' -32768 = Forms
' 5 = Queries
' -32764 = Reports
' -32761 = Modules
'---------------------------------------------------------------------------
-----
'Change Field Size (for text fields)
'The function ChangeFieldSize works both if the table is linked or local,
because the code checks what kind of table it is. This calls GetIndexes
which is listed separately at the bottom of this page. The subroutine
CallChangeFieldSize has sample code to call the function.
Function ChangeFieldSize(TblName As String, FldName As String, NewSize As
Byte) Dim Td As TableDef Dim db As Database Dim DbPath As Variant Dim FldPos
As Integer Dim rs As Recordset Dim IdxNames As Variant Dim IdxFldName As
String Dim IdxNum As Integer Dim x As Integer
'get back end path of linked table
DbPath = DLookup("Database", "MSysObjects", "Name='" & TblName & "' And
Type=6")
If IsNull(DbPath) Then
Set db = CurrentDb 'if local table
Else
Set db = OpenDatabase(DbPath) 'if linked table
If Err <> 0 Then
'failed to open back end database
Exit Function
End If
'in case back end has different table name than front end
TblName = DLookup("ForeignName", "MSysObjects", "Name='" & TblName &
"' And Type=6")
End If
'get table
Set Td = db.TableDefs(TblName)
If Err <> 0 Then
'failed to get table
GoTo Done
End If
'change field size
If Td.Fields(FldName).Size <> NewSize Then
With Td
On Error Resume Next
If NewSize > 0 And NewSize < 256 Then 'text field
.Fields.Append .CreateField("TempFld", dbText, NewSize)
Else '0 is memo field
.Fields.Append .CreateField("TempFld", dbMemo)
End If
.Fields("TempFld").AllowZeroLength = True 'personal preference
FldPos = .Fields(FldName).OrdinalPosition
.Fields("TempFld").OrdinalPosition = FldPos
Set rs = db.OpenRecordset(TblName)
While Not rs.EOF
rs.Edit
rs!TempFld = rs.Fields(FldName)
rs.Update
rs.MoveNext
Wend
rs.Close
'get indexes used by this field
IdxNames = GetIndexes(Td, FldName)
'temporarily delete indexes used by this field
For IdxNum = UBound(IdxNames, 2) To 0 Step -1
If IdxNames(0, IdxNum) > "" Then .Indexes.Delete IdxNames(0,
IdxNum)
Next
'delete old field
.Fields.Delete FldName
'rename new field to original
.Fields("TempFld").Name = FldName
'restore indexes
For IdxNum = 0 To UBound(IdxNames, 2)
If IdxNames(0, IdxNum) > "" Then
Dim Idx As Index
Set Idx = .CreateIndex(IdxNames(0, IdxNum))
'parse comma-delimited field names and add them to index
While Len(IdxNames(8, IdxNum)) > 1
x = InStr(IdxNames(8, IdxNum), ",")
IdxFldName = Left(IdxNames(8, IdxNum), x - 1)
Idx.Fields.Append Td.CreateField(IdxFldName)
IdxNames(8, IdxNum) = Mid(IdxNames(8, IdxNum), x +
1)
Wend
'assign properties to index
For x = 1 To 7
Idx.Properties(x) = IdxNames(x, IdxNum)
Next
'add the index
.Indexes.Append Idx
End If
Next
End With
If Err <> 0 Then GoTo Done
End If
ChangeFieldSize = True 'defaults to false if it fails to get here
Done:
If Not db Is Nothing Then db.Close
End Function
Sub CallChangeFieldSize()
Dim Result As Boolean
'sample call:
Result = ChangeFieldSize("Table1", "Field1", 15) Debug.Print Result End Sub
'---------------------------------------------------------------------------
-----
'Get Indexes In Table
'Access won't let you change a field type or a field size if that field
belongs to an index. Therefore, it's necessary to delete the index, modify
the field, and restore the index. The function GetIndexes finds all the
indexes containing the given field. It returns an array containing the index
names and all the index properties so that you can restore them later. This
function is called by the functions ChangeFieldSize and ChangeFieldType
above.
Function GetIndexes(Td As TableDef, FldName As String) 'Returns array of
indexes containing the specified field, ' the first index starting at
Idx(1), so that ' Ubound(2, Idx) equals the number of indexes having the
specified field Dim IdxNum As Integer, FldNum As Integer, PropNum As Integer
Dim IdxNames() As String 'array to hold indexes ReDim IdxNames(8, 0) 'first
dimension contains the index properties and field names
'second dimension represents index number Dim FldNames As
String
For IdxNum = 0 To Td.Indexes.Count - 1
FldNames = ""
For FldNum = 0 To Td.Indexes(IdxNum).Fields.Count - 1
'concatonate field names
FldNames = FldNames & Td.Indexes(IdxNum).Fields(FldNum).Name &
","
'if index contains the field we're looking for ...
If FldName = Td.Indexes(IdxNum).Fields(FldNum).Name Then
If IdxNum > 0 Then ReDim Preserve IdxNames(8, IdxNum)
'properties go into first 7 places of first dimension
For PropNum = 0 To 7
IdxNames(PropNum, IdxNum) =
Td.Indexes(IdxNum).Properties(PropNum)
Next
End If
Next
'field names go into 8th place of first dimension
If IdxNames(8, UBound(IdxNames, 2)) = "" Then IdxNames(8,
UBound(IdxNames, 2)) = FldNames
Next
GetIndexes = IdxNames
End Function
-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Steve Schapel
Sent: Thursday, February 28, 2013 11:05 PM
To: AccessD at databaseadvisors.com
Subject: [AccessD] changing Field Size programmatically
Hi. Anyone know how to do this?...
I have a number of fields, all of them Text data type, in a backend Access
2003 database, that I want to change the Field Size property.
Aside from getting hold of each copy of the mdb file, and manually editing,
is there a way I can do this in code from within the Frontend application?
Thanks.
Regards
Steve
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