Reputation: 316
I've been trying to figure out a way to use Visual Basic to work with an Access database, but all of the libraries (ADODB, etc.) that I've seen referenced on the internet either don't exist in VS2013 or don't have all the features that I'd like to use, like Recordset objects (OleDb is one such library). Is this just a case of 'you need to install the correct library'? Or am I missing some new standard with working with Microsoft databases?
Upvotes: 0
Views: 5568
Reputation: 316
It turns out I was, in fact, using the wrong classes. The page here (thanks @Plutonix) makes references to the DataSet11 and OleDbAdapter1 objects, which when used in conjunction, appear to have the sort of functionality I saw in the old DAO and ADO Recordset objects.
Upvotes: 1
Reputation: 3218
I have an ASP.NET website using VB.NET an a simple Microsoft Access 2000 database backend. I actually wrote my own custom classes to get certain tables and queries and data from the database, and it is based on OleDb. It's not the finest code available, and it is a bit shameful, actually. But it gets the job done for the simple application I'm using it for.
Cut version of file AccessDatabase.vb
Imports Microsoft.VisualBasic
Imports System.Data.OleDb
Public Class AccessDatabase
Friend db As New OleDbConnection
Private sPath As String
Public Sub New(ByRef sPath As String)
GetDatabase(sPath)
End Sub
'Use Server.MapPath("App_Data\WebContent.mdb") to load the database.
Private Function GetDatabase(ByRef sPath As String) As OleDbConnection
Try
If db.State <> System.Data.ConnectionState.Open Then
db = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & sPath)
db.Open()
End If
Catch e As Exception
Throw New Exception("Exception encountered when attempting to open database " & sPath, e)
End Try
Return db
End Function
Public Function GetTable(ByRef sTableName As String, Optional ByRef sWhere As String = "", Optional ByRef sSort As String = "") As AccessData
Dim a As New AccessData(Me)
a.SetTable(sTableName, sWhere, sSort)
Return a
End Function
Public Sub Close()
If db.State <> Data.ConnectionState.Closed Then
db.Close()
End If
End Sub
Protected Overrides Sub Finalize()
Try
If Not db Is Nothing Then
If db.State <> Data.ConnectionState.Closed Then
db.Close()
End If
End If
Catch ex As Exception
End Try
End Sub
End Class
Cut version of File AccessData.vb
Imports Microsoft.VisualBasic
Imports System.Data.OleDb
Public Class AccessData
Private db As AccessDatabase
Private data As OleDbDataReader
Public Sub New(ByRef d As AccessDatabase)
SetDB(d)
End Sub
Public Sub New(ByRef d As AccessDatabase, ByRef sTableName As String, Optional ByRef sWhere As String = "", Optional ByRef sSort As String = "")
SetDB(d)
SetTable(sTableName, sWhere, sSort)
End Sub
Public Sub SetDB(ByRef d As AccessDatabase)
db = d
End Sub
Public Sub SetTable(ByRef sTableName As String, Optional ByRef sWhere As String = "", Optional ByRef sSort As String = "")
If sWhere = "" And sSort = "" Then
SetFromQuery("SELECT " & sTableName & ".* FROM " & sTableName)
ElseIf sSort = "" Then
SetFromQuery("SELECT " & sTableName & ".* FROM " & sTableName & " WHERE " & sWhere)
ElseIf sWhere = "" Then
SetFromQuery("SELECT " & sTableName & ".* FROM " & sTableName & " ORDER BY " & sSort)
Else
SetFromQuery("SELECT " & sTableName & ".* FROM " & sTableName & " WHERE " & sWhere & " ORDER BY " & sSort)
End If
End Sub
Public Sub SetFromQuery(ByRef sQuery As String)
Dim c As OleDbCommand
c = New OleDbCommand(sQuery, db.db)
data = c.ExecuteReader()
End Sub
'Returns the value of the requested field of the current row of the reader
Public Function GetValue(ByRef sField As String) As String
Dim iOrdinal As Integer
Try
iOrdinal = data.GetOrdinal(sField)
If Not data.GetValue(iOrdinal).Equals(DBNull.Value) Then
Return data.GetValue(iOrdinal).ToString()
End If
Catch e As System.IndexOutOfRangeException
Throw New System.IndexOutOfRangeException("Field '" & sField & "' was requested from " & vbCrLf & sQuery & "," & vbCrLf & "but it does not exist.", e)
Catch e As System.InvalidOperationException
Throw New System.InvalidOperationException("No data exists for the current row in field '" & sField & "'. Make sure you have performed a Read() operation and that you are not at the EOF or BOF of the data stream.", e)
End Try
Return ""
End Function
'This will close the stream when data.Read() returns false
Public Function Read() As Boolean
Dim bResult As Boolean
bResult = data.Read()
If Not bResult Then
data.Close()
End If
Return bResult
End Function
End Class
Upvotes: 0