UltraLite ActiveX User's Guide
  Tutorial: An UltraLite Application for PocketPC
    Lesson 3: Write the 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 connection string to connect to the database. For an example using a ULConnectionParms object, see Lesson 3: Write the eMbedded Visual Basic sample code.

Write code to connect to the 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 CustomerTable As ULTable
   Dim colID, colFirstName, colLastName As ULColumn

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. The database manager then tries to open a connection to the database specified by the connection string. If the database does not exist, it creates a new database using the given schema.

   Sub Form_Load()
     Dim conn_parms As String
     Dim open_parms As String
     Dim schema_parms As String
     On Error Resume Next
     conn_parms = "uid=DBA;pwd=SQL"
     open_parms = conn_parms & ";ce_file=\Program Files\tutorial\tutCustomer.udb"
     schema_parms = open_parms & ";ce_schema=\Program Files\tutorial\tutCustomer.usm"
     Set DatabaseMgr = CreateObject("UltraLite.ULDatabaseManager")
     Set Connection = DatabaseMgr.OpenConnection(open_parms)
     If Err.Number = UlSQLCode.ulSQLE_NOERROR Then
       MsgBox "Connected to an existing database."
     ElseIf Err.Number = UlSQLCode.ulSQLE_DATABASE_NOT_FOUND Then
       Err.Clear
       Set Connection = DatabaseMgr.CreateDatabase(schema_parms)
       If Err.Number <> 0 Then
         MsgBox Err.Description
         Else
         MsgBox "Connected to a new database"  
       End If
     End If
   End Sub

4. Run the application.

   • Choose Run > Execute.

   • After an initial message box, the form loads.

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

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