TableDef Object

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Access Developer Reference

A TableDef object represents the stored definition of a base table or a linked table (Microsoft Access workspaces only).

Remarks

You manipulate a table definition using a TableDef object and its methods and properties. For example, you can:

  • Examine the field and index structure of any local, linked, or external table in a database.
  • Use the Connect and SourceTableName properties to set or return information about linked tables, and use the RefreshLink method to update connections to linked tables.
  • Use the ValidationRule and ValidationText properties to set or return validation conditions.
  • Use the OpenRecordset method to create a table–, dynaset–, dynamic–, snapshot–, or forward–only–type Recordset object, based on the table definition.

For base tables, the RecordCount property contains the number of records in the specified database table. For linked tables, the RecordCount property setting is always –1.

To create a new TableDef object, use the CreateTableDef method.

To add a field to a table

  1. Make sure any Recordset objects based on the table are all closed.
  2. Use the CreateField method to create a Field object variable and set its properties.
  3. Use the Append method to add the Field object to the Fields collection of the TableDef object.

You can delete a Field object from a TableDefs collection if it doesn't have any indexes assigned to it, but you will lose the field's data.

To create a table that is ready for new records in a database

  1. Use the CreateTableDef method to create a TableDef object.
  2. Set its properties.
  3. For each field in the table, use the CreateField method to create a Field object variable and set its properties.
  4. Use the Append method to add the fields to the Fields collection of the TableDef object.
  5. Use the Append method to add the new TableDef object to the TableDefs collection of the Database object.

A linked table is connected to the database by the SourceTableName and Connect properties of the TableDef object.

  1. Use the CreateTableDef method to create a TableDef object.
  2. Set its Connect and SourceTableName properties (and optionally, its Attributes property).
  3. Use the Append method to add it to the TableDefs collection of a Database.

To refer to a TableDef object in a collection by its ordinal number or by its Name property setting, use any of the following syntax forms:

TableDefs(0)

TableDefs("name")

TableDefs![name]

Example

This example creates a new TableDef object and appends it to the TableDefs collection of the Northwind Database object. It then enumerates the TableDefs collection and the Properties collection of the new TableDef.

Visual Basic for Applications 
  Sub TableDefX()

Dim dbsNorthwind As Database
Dim tdfNew As TableDef
Dim tdfLoop As TableDef
Dim prpLoop As Property


Set dbsNorthwind = OpenDatabase("Northwind.mdb")


' Create new TableDef object, append Field objects
' to its Fields collection, and append TableDef
' object to the TableDefs collection of the
' Database object.
Set tdfNew = dbsNorthwind.CreateTableDef("NewTableDef")
tdfNew.Fields.Append tdfNew.CreateField("Date", dbDate)
dbsNorthwind.TableDefs.Append tdfNew


With dbsNorthwind
Debug.Print .TableDefs.Count & _
" TableDefs in " & .Name


  ' Enumerate TableDefs collection.
  For Each tdfLoop In .TableDefs
     Debug.Print "  " & tdfLoop.Name
  Next tdfLoop

  With tdfNew
     Debug.Print "Properties of " & .Name

     ' Enumerate Properties collection of new
     ' TableDef object, only printing properties
     ' with non-empty values.
     For Each prpLoop In .Properties
        Debug.Print "  " & prpLoop.Name & " - " & _
           IIf(prpLoop = "", "[empty]", prpLoop)
     Next prpLoop

  End With

  ' Delete new TableDef since this is a 
  ' demonstration.
  .TableDefs.Delete tdfNew.Name
  .Close



End With


End Sub

This example creates a new TableDef object in the Northwind database.

Visual Basic for Applications 
  Sub CreateTableDefX()

Dim dbsNorthwind As Database
Dim tdfNew As TableDef
Dim prpLoop As Property


Set dbsNorthwind = OpenDatabase("Northwind.mdb")


' Create a new TableDef object.
Set tdfNew = dbsNorthwind.CreateTableDef("Contacts")


With tdfNew
' Create fields and append them to the new TableDef
' object. This must be done before appending the
' TableDef object to the TableDefs collection of the
' Northwind database.
.Fields.Append .CreateField("FirstName", dbText)
.Fields.Append .CreateField("LastName", dbText)
.Fields.Append .CreateField("Phone", dbText)
.Fields.Append .CreateField("Notes", dbMemo)


  Debug.Print "Properties of new TableDef object " & _
     "before appending to collection:"

  ' Enumerate Properties collection of new TableDef 
  ' object.
  For Each prpLoop In .Properties
     On Error Resume Next
     If prpLoop <> "" Then Debug.Print "  " & _
       prpLoop.Name & " = " & prpLoop
     On Error GoTo 0
  Next prpLoop

  ' Append the new TableDef object to the Northwind 
  ' database.
  dbsNorthwind.TableDefs.Append tdfNew

  Debug.Print "Properties of new TableDef object " & _
     "after appending to collection:"

  ' Enumerate Properties collection of new TableDef 
  ' object.
  For Each prpLoop In .Properties
     On Error Resume Next
     If prpLoop <> "" Then Debug.Print "  " & _
       prpLoop.Name & " = " & prpLoop
     On Error GoTo 0
  Next prpLoop



End With


' Delete new TableDef object since this is a
' demonstration.
dbsNorthwind.TableDefs.Delete "Contacts"


dbsNorthwind.Close

See Also