Creating Relationships in Access - vb.net

Question

I got two tables in my access file. and I would like to create relationship between them. The following diagram is the relationship I created manually in Access.
However, I want to create the relationships in VB.net and here is my code:
conn.Open()
daBooks = New OleDb.OleDbDataAdapter("SELECT * FROM Books", conn)
daAuthor = New OleDb.OleDbDataAdapter("SELECT * FROM authors", conn)
daBooks.Fill(ds, "Books")
daAuthor.Fill(ds, "authors")
conn.Close()
'Set the relation
Dim parentColumn As DataColumn
parentColumn = ds.Tables("authors").Columns("AuthorID")
Dim childColumn As DataColumn = New DataColumn
Try
childColumn = ds.Tables("Books").Columns("AuthorID")
Catch ex As Exception
MsgBox(ex.Message)
Exit Sub
End Try
Dim a As String
a = ds.Tables("authors").Rows(0).Item("AuthorID")
Dim b As String
b = ds.Tables("Books").Rows(0).Item("AuthorID")
Dim relation As DataRelation = New _
System.Data.DataRelation("Books_Authors", parentColumn, childColumn)
ds.Relations.Add(relation)
RelationName.Text = relation.RelationName
'End of setting relation
Dim cb1 As New OleDb.OleDbCommandBuilder(daBooks)
Dim cb2 As New OleDb.OleDbCommandBuilder(daAuthor)
Try
daBooks.Update(ds, "books")
Catch ex As Exception
MsgBox(ex.Message)
End Try
daAuthor.Update(ds, "authors")
However after I ran the code, it couldn't change the database. Can anyone help me with this so that I can create a new relationship for two tables in VB.NET.
Generally I think the problem is that the System.Data.DataRelation and ds.Relations.Add(relation) just create the relationship for the dataset but it hasn't been updated to the database through dataadapter or something else. Am I correct by saying so or it's because of other reasons. If I'm correct, then how to update the dataset to database?

Answer 1

You can create that relationship by executing an ALTER TABLE statement from your OleDb connection.
ALTER TABLE Books
ADD CONSTRAINT BooksRelationship
FOREIGN KEY (AuthorID) REFERENCES Authors (AuthorID);

Answer 2

You can create a macro in Access that creates a relationship between your tables and run it via VB.NET.
Here is a function to create a relation in MS Access:
Public Function MacroCreateRelation()
Dim db As DAO.Database
CreateRelation("Author", "IdAuthor", _
"Book", "IdAuthor")
Set db = Nothing
End Function
Private Function CreateRelation(primaryTblName As String, _
primaryFieldName As String, _
foreignTblName As String, _
foreignFieldName As String) As Boolean
On Error GoTo ErrHandler
Dim myDB As DAO.Database
Dim newRelation As DAO.Relation
Dim relatingField As DAO.Field
Dim relationName As String
relationName = primaryTblName + "_" + primaryFieldName + _
"__" + foreignTblName + "_" + foreignFieldName
Set myDB = CurrentmyDB()
' First create the relation
Set newRelation = myDB.CreateRelation(relationName, _
primaryTblName, foreignTblName)
'field of the primary table
Set relatingField = newRelation.CreateField(primaryFieldName)
'Then the field of the the second table
relatingField.ForeignName = foreignFieldName
'now just add the field to the relation
newRelation.Fields.Append relatingField
'Last but not least add the relation to the db
myDB.Relations.Append newRelation
Set myDB = Nothing
return True
Exit Function
ErrHandler:
Debug.Print Err.Description + " [ " + relationName + "]"
return False
End Function
Then you have just to call the macro from VB.NET.