1/36 Database Programming with Visual Basic.Net and MS Access IKE Lab. Yunho Song Database Management and Analysis

2/36 Database Programming with Visual Basic.Net and MS Access Contents 1.Installation 2.VB.NET and Database 1.The Database Wizard (Visual Studio users) 2.Write your own VB.NET database code 3.Learn about DataSets and Data Adaptors 4.Display the Data in the DataSet 5.Navigate a Database with VB.NET 6.How to Move through the Database 7.Add, Update and Delete Records 8.Add a New Record using VB.NET 9.Delete a Record using VB.NET 10. A VB.NET Database Project

1. Installation

4/36 Installation 1. Installation Database Programming with Visual Basic.Net and MS Access

5/36 1. Installation Database Programming with Visual Basic.Net and MS Access Installation

6/36 1. Installation Database Programming with Visual Basic.Net and MS Access Installation

7/36 1. Installation Database Programming with Visual Basic.Net and MS Access First run - choose the default environment settings Installation

2. VB.NET and Database

9/36 VB.NET and Database Let's make a start on our Database project  Click File > New Project from the menu bar  Select Windows Application, and then give it the Name AddressBook. Click OK  Locate the Solution Explorer on the right hand side Database Programming with Visual Basic.Net and MS Access 2.1. Database Wizard  Select Data Sources

10/36 VB.NET and Database The Wizard display all your tables, fields and objects Database Programming with Visual Basic.Net and MS Access 2.1. Database Wizard

11/36 VB.NET and Database The Data Sources area displays information about your database Database Programming with Visual Basic.Net and MS Access 2.1. Database Wizard  Click the plus symbol next to tblContacts

12/36 VB.NET and Database To add a Field to your Form Database Programming with Visual Basic.Net and MS Access 2.1. Database Wizard  A textbox and a label will be added

13/36 VB.NET and Database Run your program by hitting the F5 key Database Programming with Visual Basic.Net and MS Access 2.1. Database Wizard  Drag and Drop more Fields to your form

14/36 The Connection Object  What you need if you want to connect to a database  OLE(Object Linking and Embedding) allow you to connect to data sources in general, and not just databases. You can use it, for example, to connect to text files, SQL Server, , and a whole lot more  Place a button on your form. Change the Name property to btnLoad Double click your button to open up the code window Add the following line: Database Programming with Visual Basic.Net and MS Access 2.2. Write your own Database code VB.NET and Database Dim con As New OleDb.OleDbConnection  At the top of your code window, before Public Class Form 1, type the following: Imports System.Data

15/36 Database Programming with Visual Basic.Net and MS Access 2.2. Write your own Database code VB.NET and Database Coding window will look like this  Get a pop up box from where you can select OleDbConnection  Use to connect to an Access database

16/36 Database Programming with Visual Basic.Net and MS Access 2.2. Write your own Database code VB.NET and Database Setting a Connection String  The technology is called the Provider; and you use "Data Source" to specify where your database is con.ConnectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source = C:\AddressBook.mdb"  The first part specifies which provider technology we want to use to do the connecting (JET)  The second part, typed after a semi-colon, points to where the database is  In the above code, the database is on the C drive, in the root folder. The name of the Access file we want to connect to is called AddressBook.mdb

17/36 Database Programming with Visual Basic.Net and MS Access 2.2. Write your own Database code VB.NET and Database Opening the Connection  Open method of the Connection Object:  Close method of the Connection Object: con.Open( ) MsgBox("A Connection to the Database is now open“) con.Close() MsgBox("The Connection to the Database is now Closed“)

18/36 Database Programming with Visual Basic.Net and MS Access 2.2. Write your own Database code VB.NET and Database Coding window Test out our code

19/36 Database Programming with Visual Basic.Net and MS Access 2.3. Data Sets and Data Adapters VB.NET and Database Data Sets  Hidden from you, and just stored in memory  Imagine a grid with rows and columns. Each imaginary row of the DataSet represents a Row of information in your Access database. And each imaginary column represents a Column of information in your Access database (called a Field in Access) Data Adapter  The Connection Object and the DataSet can't see each other  They need a go-between so that they can communicate  This go-between is called a Data Adapter  The Data Adapter contacts your Connection Object, and then executes a query that you set up. The results of that query are then stored in the DataSet.

20/36 Database Programming with Visual Basic.Net and MS Access 2.3. Data Sets and Data Adapters VB.NET and Database Data Adapter and DataSet are objects  OleDb.OleDbDataAdapter Called da Hold a reference to the Data Adapter  da = New OleDb.OleDbDataAdapter(sql, con) creates a new Data Adapter object Need to put two things in the round brackets of the Object declaration SQL string (which we'll get to shortly), and connection object Connection Object is stored in the variable called con  Data Adaptor acting as a go-between for the Connection Object and the Data Set Dim ds As New DataSet Dim da As OleDb.OleDbDataAdapter da = New OleDb.OleDbDataAdapter(sql, con)

21/36 Database Programming with Visual Basic.Net and MS Access 2.3. Data Sets and Data Adapters VB.NET and Database Structured Query Language(SQL)  A way to query and write to databases Hold a reference to the Data Adapter  To select just the first name and surname columns from our database  To SELECT all (*) the records from the table called tblContacts Select * from Table_Name SELECT tblContacts.FirstName, tblContacts.Surname FROM tblContacts sql = "SELECT * FROM tblContacts”

22/36 Database Programming with Visual Basic.Net and MS Access 2.3. Data Sets and Data Adapters VB.NET and Database Structured Query Language(SQL) Dim ds As New DataSet Dim da As OleDb.OleDbDataAdapter Dim sql As String sql = "SELECT * FROM tblContacts" da = New OleDb.OleDbDataAdapter(sql, con)

23/36 Database Programming with Visual Basic.Net and MS Access 2.3. Data Sets and Data Adapters VB.NET and Database Filling the DataSet  Data Adapter can Fill a DataSet with records from a Table  The DataSet (ds) will now be filled with the records we selected from the table called tblContact  One slight problem - nobody can see the data yet! We'll tackle that in the next part da = New OleDb.OleDbDataAdapter(sql, con) da.Fill(ds, "AddressBook“)

24/36 Database Programming with Visual Basic.Net and MS Access 2.4. Displaying the Data in the DataSet VB.NET and Database To display the records on a Form  Add two textboxes to your form  Change the Name properties of your textboxes to txtFirstName and txtSurname  Go back to your code window  Add the following two lines: txtFirstName.Text = ds.Tables("AddressBook").Rows(0).Item(1) txtSurname.Text = ds.Tables("AddressBook").Rows(0).Item(2)

25/36 Database Programming with Visual Basic.Net and MS Access 2.5. Navigate a Database VB.NET and Database To see a more practical example  Add two Textboxes. Change the Name properties to txtFirstName and txtSurname  Add four Buttons. Change the Name and Text properties to these: Button NameButton Text btnNext btnPrevious btnFirst btnLast Next Record Previous Record First Record Last Record

26/36 Database Programming with Visual Basic.Net and MS Access 2.5. Navigate a Database VB.NET and Database To see a more practical example  Add the following code to the Form1 Declarations area:  When the Form Loads, we can connect to our database, use the data Adaptor to grab some records from the database and then put these records into the DataSet So in the Form1 Load Event, add the following code:

27/36 Database Programming with Visual Basic.Net and MS Access 2.5. Navigate a Database VB.NET and Database To see a more practical example  You've met all the code before, except for these two lines:  In the MaxRows variable, we can store how many rows are in the DataSet  Get how many rows are in DataSet with Rows.Count: To navigate through the records  Use inc variable. We'll either add 1 to it, or take 1 away  Use the variable for the Rows in the DataSet  It's better to do this in a Subroutine of own  So add this Sub to code: MaxRows = ds.Tables("AddressBook").Rows.Count inc = -1 Private Sub NavigateRecords() txtFirstName.Text = ds.Tables("AddressBook").Rows(inc).Item(1) txtSurname.Text = ds.Tables("AddressBook").Rows(inc).Item(2) End Sub

28/36 Database Programming with Visual Basic.Net and MS Access 2.5. Navigate a Database VB.NET and Database The important part is Rows(inc). This moves us through the Rows in the DataSet. Then placing the values into the two Textboxes

29/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database How to Move Forward One Record at a Time  Double click your Next Record button to access the code 2.6. How to Move through the Database Move Back One Record at a Time  to add to your btnPrevious: If inc > 0 Then inc = inc - 1 NavigateRecords() ElseIf inc = -1 Then MsgBox("No Records Yet") ElseIf inc = 0 Then MsgBox("First Record") End If If inc <> MaxRows - 1 Then inc = inc + 1 NavigateRecords() Else MsgBox("No More Rows") End If

30/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database Moving to the Last Record in the DataSet  to add to your btnLast: 2.6. How to Move through the Database If inc <> MaxRows - 1 Then inc = MaxRows - 1 NavigateRecords() End If Moving to the First Record in the DataSet  to add to your btnFirst: If inc <> 0 Then inc = 0 NavigateRecords() End If

31/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database DataSet is disconnected from the database  Not adding the record to the database: adding it to the DataSet How to add, delete, update new records  Add five more buttons to your form 2.7. Add, Update and Delete Records  Change the Name properties btnAddNew btnCommit btnUpdate btnDelete btnClear

32/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database Updating a Record  The changes will just get made to the DataSet  Add the following code to btnUpdate: 2.7. Add, Update and Delete Records ds.Tables("AddressBook").Rows(inc).Item(1) = txtFirstName.Text ds.Tables("AddressBook").Rows(inc).Item(2) = txtSurname.Text MsgBox("Data updated“) "Changes are made to the DataSet, and NOT to the Database“  To update the database, Add following code Dim cb As New OleDb.OleDbCommandBuilder(da) ds.Tables("AddressBook").Rows(inc).Item(1) = txtFirstName.Text ds.Tables("AddressBook").Rows(inc).Item(2) = txtSurname.Text da.Update(ds, "AddressBook") MsgBox("Data updated“)

33/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database Add a New Record  Add New Record button: 2.8. How to Add a New Record btnCommit.Enabled = True btnAddNew.Enabled = False btnUpdate.Enabled = False btnDelete.Enabled = False txtFirstName.Clear() txtSurname.Clear() The Clear/Cancel button can be used to switch it back on again  Add this code to btnClear: btnCommit.Enabled = False btnAddNew.Enabled = True btnUpdate.Enabled = True btnDelete.Enabled = True inc = 0 NavigateRecords()

34/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database To add a new record to the database  Add this code to btnCommit 2.8. How to Add a New Record If inc <> -1 Then Dim cb As New OleDb.OleDbCommandBuilder(da) Dim dsNewRow As DataRow dsNewRow = ds.Tables("AddressBook").NewRow() dsNewRow.Item("FirstName") = txtFirstName.Text dsNewRow.Item("Surname") = txtSurname.Text ds.Tables("AddressBook").Rows.Add(dsNewRow) da.Update(ds, "AddressBook“) MsgBox("New Record added to the Database“) btnCommit.Enabled = False btnAddNew.Enabled = True btnUpdate.Enabled = True btnDelete.Enabled = True End If

35/36 Database Programming with Visual Basic.Net and MS Access VB.NET and Database Deleting Records from a Database  Add this code to btnDelete 2.8. Delete a Record from a Database Dim cb As New OleDb.OleDbCommandBuilder(da) ds.Tables("AddressBook").Rows(inc).Delete() MaxRows = MaxRows - 1 inc = 0 NavigateRecords() da.Update(ds, "AddressBook“)  To display a message box asking users if they really want to delete this record If MessageBox.Show("Do you really want to Delete this Record?", _ "Delete", MessageBoxButtons.YesNo, _ MessageBoxIcon.Warning) = DialogResult.No Then MsgBox("Operation Cancelled") Exit Sub End If

36/36 Thank You!!