UltraLite ActiveX User's Guide
  Tutorial: Using Dynamic SQL in an UltraLite Application for PocketPC
    Lesson 3: Write the eMbedded Visual Basic sample code

Write code to connect to your database

In this application, you connect to the database during the Form_Load event. You can also connect to a database using the general module.

This example uses a ULConnectionParms object to connect to the database. For an example using a connection string, see Lesson 3: Write the eMbedded Visual Basic sample code.

Write code to connect to an UltraLite database

1. Double-click the form to open the Code window.

2. Declare the required UltraLite objects.

   Enter the following code in the General area of your form.

   Dim DatabaseMgr As ULDatabaseManager
   Dim Connection As ULConnection
   Dim myPrepStmt As ULPreparedStatement
   Dim MyResultSet As ULResultSet

3. Add code to connect to the database in the Form_Load event.

   In the code below, CreateObject is used to create the initial database manager object. It then tries to open a connection to the database specified by the ULConnectionParms object. If the database does not exist, it creates a new database using the given schema.

   Sub Form_Load()
     ' Use CreateObject to get an instance of the Database Manager object
     Set DatabaseMgr = CreateObject("UltraLite.ULDatabaseManager")
     ' Create a LoginParms object, using CreateObject
     Dim LoginParms As ULConnectionParms
     Set LoginParms = CreateObject("UltraLite.ULConnectionParms")
     LoginParms.DatabaseOnCE = "\Program Files\tutorial\tutorial.udb"
     LoginParms.SchemaOnCE = "\Program Files\tutorial\tutorial.usm"
     LoginParms.CacheSize = "128k"
     On Error Resume Next
     ' Use the "WithParms" calls
     Set Connection = _
           DatabaseMgr.OpenConnectionWithParms(LoginParms)
     If Err.Number = ULSQLCode.ulSQLE_NOERROR Then
       MsgBox "Connected to an existing database"
     ElseIf Err.Number = _
             ULSQLCode.ulSQLE_ULTRALITE_DATABASE_NOT_FOUND Then
       Err.Clear
       Set Connection = _
          DatabaseMgr.CreateDatabaseWithParms(LoginParms)
       If Err.Number = ULSQLCode.ulSQLE_NOERROR Then
         MsgBox "Connected to a new database"
       Else
         MsgBox Err.Description
       End If
     End If
     Set MyPrepStmt = _
        Connection.PrepareStatement("SELECT id, name FROM names")
     Set MyResultSet = MyPrepStmt.ExecuteQuery
         MyResultSet.MoveFirst
   End Sub

4. Write the code that ends the application and closes the connection when the End button is clicked.

   Sub btnDone_Click()
     Connection.Close
   End Sub

5. Run the application.

   • Choose Run > Execute.

   • After an initial message, the form loads.

   • Click OK in the top right corner to terminate the application.

6. Use the File Viewer to check that a database file named tutorial.udb has been created on the emulator.