1. Introduction to ADO.NET

2. ADO.NET Objects .NET Applications Data Set Data Reader Command Object
Connection Object
Managed Data Provider
(OLEDB)
Database

3. Connection with a Connection Object
A connection object represents a unique session with a data source.
Connection string: database, OLE DB provider, password, if any, security, etc.
Use the Open/Close method to open/close a connection.
Manage transaction: BeginTransaction(), Commit, rollBack.

4. Connection String
Containing information about database, OLE DB provider, password, if any, security, etc.
For Jet database:
Provider=Microsoft.Jet.OLEDB.4.0;Persist Security info = False;Data Source=c:\ …\Nwind.mdb

5. Data Link Properties (Under the Advanced Tab of the Connection Dialog Window)
Access permissions
Read—Read only.
ReadWrite—Read and write.
Share Deny None—Neither read nor write access can be denied to others.
Share Deny Read—Prevents others from opening in read mode.
Share Deny Write—Prevents others from opening in write mode.
Share Exclusive—Prevents others from opening in read/write mode.
Write—Write only.

6. Providers MSDASQL Microsoft.Jet.OLEDB.3.51 Microsoft.Jet.OLEDB.4.0
Microsoft OLE DB Provider for ODBC
Microsoft.Jet.OLEDB.3.51
Microsoft.Jet.OLEDB.4.0
MSDAORA – For Oracle
SQLOLEDB – Microsoft SQL Server

7. Connection Object Basic Methods: Open, Close BeginTransaction Example:
dim strConn as string ="Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
dim objConn as new OledbConnection(strConn)
objConn.open()
Basic Methods:
Open, Close
BeginTransaction

8. Command Object
The command object allows us to execute a SQL statement.
Properties:
CommandType: SQL or stored procedure
CommandText: SQL statement
Connection
Basic Methods:
ExecuteReader: Creates a DataReader object that contains the results of the query.
ExecuteNonQuery: Execute SQL’s INSERT, DELETE, UPDATE statements.

9. ExecuteReader Example
dim strConn as string ="Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
dim objConn as new OledbConnection(strConn)
dim strSQL as string = "select * from customer;"
dim objComm as new OledbCommand(strSQL,objConn)
dim Results as string
objConn.open()
dim objDataReader as oledbDataReader
objDataReader=objComm.executeReader()

10. Import NameSpace
The Imports statement must appear before all other declarations in a file and cannot appear inside a class or module declaration.
Imports System.Data.OleDb
Public Class Form1

11. DataReader Object It is read-only and forward-only cursor.
Basic Methods:
Read: Reads the current record and advances the pointer to the next record.
Close: Closes the dataReader.

12. Read Records in a DataReader
dim Results as string
do while objDataReader.Read()=true
Results+=objDataReader("cid") + “ “ + objDataReader("Cname") + vbCrLF
loop
Textbox1.text=Results
Note: objDataReader.Item(0)
Note: objDataReader.Item(“cid”)

13. Add Items from a DataReader to a Listbox
Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Dim objConn As New OleDbConnection(strConn)
Dim strSQL As String = "select cname from customer;"
Dim objComm As New OleDbCommand(strSQL, objConn)
objConn.Open()
Dim objDataReader As OleDbDataReader
objDataReader = objComm.ExecuteReader()
Do While objDataReader.Read() = True
LISTBOX1.Items.Add(objDataReader("cname"))
Loop
Note: 1. Listbox is not bound. 2. SelectedItem

14. To Reuse a DataReader objDataReader.Close()
objDataReader = objComm.ExecuteReader()

15. Error Handling Try objConn.Open() Dim objDataReader As OleDbDataReader
objDataReader = objComm.ExecuteReader()
Do While objDataReader.Read() = True
Results += objDataReader("cid") + " " + objDataReader("Cname") + vbCrLf
Loop
TextBox1.Text = Results
objConn.Close()
Catch except As System.Exception
MessageBox.Show(except.Message)
End Try

16. Possible Database Errors
SQL syntax errors
Database connection not open
Violate database constraints
Referential integrity
Field data type and length
Primary key constraint

17. ExecuteNonQuery Example
dim strSQLUpd as string="Update customer set rating = ‘A’”
strSQLUpd=strSQLUpd & " where cname='" & CnameList.selectedItem.text & "'“
Dim objCommUpd As New OleDbCommand(strSQLUpd, objConn)
objCommUpd.ExecuteNonQuery()

18. Demo Create a project that do the following tasks:
Use a DataReader to retrieve customer IDs and populate a listbox.
Select a new rating from radio buttons for the selected customer.
Update customer’s rating using the ExecuteNonQuery method of a Command object.

19. Declare OleDB objects and create listbox
Imports System.Data.OleDb
Public Class Form3
Inherits System.Windows.Forms.Form
Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Dim objConn As New OleDbConnection(strConn)
Dim strSQL As String = "select cid from customer;"
Dim objComm As New OleDbCommand(strSQL, objConn)
Private Sub Form3_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
objConn.Open()
Dim objDataReader As OleDbDataReader
objDataReader = objComm.ExecuteReader()
Do While objDataReader.Read() = True
ListBox1.Items.Add(objDataReader("cid"))
Loop
objConn.Close()
End Sub

20. Update customer rating
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
objConn.Open()
Dim newRating As String
If RadioButton1.Checked = True Then
newRating = "A"
ElseIf RadioButton2.Checked Then
newRating = "B"
Else
newRating = "C"
End If
Dim strSQLUpd As String = "Update customer set rating = '" & newRating & "'"
strSQLUpd = strSQLUpd & " where cid='" & ListBox1.SelectedItem & "'"
Dim objCommUpd As New OleDbCommand(strSQLUpd, objConn)
objCommUpd.ExecuteNonQuery()
objConn.Close()
End Sub

21. Use Command Object’s ExecuteNonQuery to Insert A New Record
Create unbound text boxes to enter new record.
Add an Insert button with the following handler
Dim strSQLInsert As String
strSQLInsert = "Insert into Customer values ('"
strSQLInsert = strSQLInsert & TextBox1.Text & "','" & TextBox2.Text & "','"
strSQLInsert = strSQLInsert & TextBox3.Text & "','" & TextBox4.Text & "')"
Dim objCommInsert As New OleDbCommand(strSQLInsert, objConn)
objCommInsert.ExecuteNonQuery()

22. DataSet Object
A DataSet object can hold several tables and relationships between tables.
A DataSet is a set of disconnedted data. Data is extracted from the database and stored in the DataSet object. Updates to the DataSet must copy back to the database to make the changes permanent.

23. DataSet and Related Objects
DataSet: Can contain multiple tables and relationships.
DataTable object: Represents a table in the dataset.
DataAdapter: This the object used to pass data between the database and the dataset. The Fill method copies the data into the dataset, and the Update method copies the updates back into the database.
DataView: This represents a specific view of the DataTables held in the dataset.

24. DataSet and Related Objects
DataView
DataSet
DataTable
DataTable
Command
DataAdapter
Connection

25. Structure of a Dataset Dataset Tables Data table Rows Data Row Columns
Data Column
Constraints
Relations
Constraint
Data Relation

26. Reading Data into a Table
dim strConn as string ="Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
dim objConn as new OledbConnection(strConn)
dim strSQL as string = "select * from customer;"
dim objDataSet as new Dataset()
dim objAdapter as new OledbDataAdapter(strSQL, objConn)
objAdapter.Fill(objDataSet, "Cust")

27. Binding a Table in a Dataset to a DataGrid
Imports System.Data.OleDb
Public Class Form4
Inherits System.Windows.Forms.Form
Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Dim objConn As New OleDbConnection(strConn)
Dim objDataSet As New DataSet()
Private Sub Form4_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim strSQL As String = "select * from customer;"
Dim objAdapter As New OleDbDataAdapter(strSQL, objConn)
objAdapter.Fill(objDataSet, "Cust")
DataGrid1.DataSource = objDataSet
DataGrid1.DataMember = "Cust"
End Sub

28. DataView Object
The DataView object exposes a complete table or a subset of the records from a table.
Table’s DefaultView property:
Dim ObjDataView As New DataView()
ObjDataView.Table = objDataSet.Tables("Cust")
Or: ObjDataView = objDataSet.Tables("Cust").DefaultView
DataView can be used as a DataSource in data binding.

29. Data Binding with DataView Object
Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Dim objConn As New OleDbConnection(strConn)
Dim objDataSet As New DataSet()
Dim strSQL As String = "select * from customer;"
Dim objAdapter As New OleDbDataAdapter(strSQL, objConn)
objAdapter.Fill(objDataSet, "Cust")
Dim ObjDataView As New DataView()
ObjDataView = objDataSet.Tables("Cust").DefaultView
DataGrid1.DataSource = ObjDataView

30. Accessing Records in DataView
Using DataView and DataRowView object’s Item property:
objdataView = objDataSet.Tables("customer").DefaultView
TextBox1.Text = objdataView.Item(rowIndex).Item(0)
TextBox2.Text = objdataView.Item(rowIndex).Item(1)
Move to the next record:
rowIndex += 1
TextBox1.Text = objdataView.Item(rowIndex).Item(0)
TextBox2.Text = objdataView.Item(rowIndex).Item(1)

31. Selecting a Subset of Records with DataView’s RowFilter Property
objDataView.RowFilter = criteria

32. DataView Example Dim ObjDataView As New DataView()
Dim newRating As String
If RadioButton1.Checked = True Then
newRating = "A"
ElseIf RadioButton2.Checked Then
newRating = "B"
Else
newRating = "C"
End If
ObjDataView.Table = objDataSet.Tables("Cust")
ObjDataView.RowFilter = "rating='" & newRating & "'"
DataGrid1.Visible = True
DataGrid1.DataSource = ObjDataView

33. Defining an Adapter without A Command Object
dim strConn as string ="Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
dim objConn as new OledbConnection(strConn)
dim strSQL as string = "select * from customer;"
dim objDataSet as new Dataset()
dim objAdapter as new OledbDataAdapter(strSQL, objConn)
objAdapter.Fill(objDataSet, "Cust")

34. Defining an Adapter with A Command Object
dim strSQLCust as string = "select * from customer;"
dim objComm as new OledbCommand()
dim objAdapter as new OledbDataAdapter()
dim objDataSet as new Dataset()
objComm.Connection=objConn
objComm.CommandType=COmmandType.Text
objComm.CommandText=strSQLCust
objAdapter.SelectCommand=objComm
objConn.open()
objAdapter.Fill(objDataSet, "Customer")
Note:Adapter has SelectCommand, InsertCommand, DeleteCommand, UpdateCommand properties (Check Object Browser).

35. Creating Multiple Tables in A DataSet
dim strSQLCust as string = "select * from customer;"
dim strSQLOrder as string ="select * from orders;"
dim objComm as new OledbCommand()
dim objAdapter as new OledbDataAdapter()
dim objDataSet as new Dataset()
objComm.Connection=objConn
objComm.CommandType=COmmandType.Text
objComm.CommandText=strSQLCust
objAdapter.SelectCommand=objComm
objConn.open()
objAdapter.Fill(objDataSet, "Customer")
objComm.COmmandText=strSQLOrder
objAdapter.Fill(objDataSet, "Orders")

36. Binding Multiple Tables to a DataGrid (Example 1)
DataGrid1.DataSource = objDataSet

37. Binding Multiple Tables to a DataGrid (Example 2)
Dim ObjDataView As New DataView()
Dim TableName As String
If RadioButton1.Checked = True Then
ObjDataView = objDataSet.Tables("Customer").DefaultView
Else
ObjDataView = objDataSet.Tables("Orders").DefaultView
End If
DataGrid1.DataSource = ObjDataView

38. Adding Relationship to a Dataset
The Dataset object has a Relations property. It is a collection of DataRelations. We can use a relationship to enforce the referential integrity.
To define a DataRelation:
DataRelObj=DataRelation(RelationName, ParentTable Field, ChildTableField)
Dim objRel As DataRelation
objRel = New DataRelation("custOrder", objDataset.tables("customer").columns("cid"), objDataset.tables("orders").columns("cid"))
Adding a relation to the dataset:
objDataSet.Relations.Add(objRel)

39. Creating a Hierarchical DataGrid
Dim objRel As DataRelation
objRel = New DataRelation("custOrder", objDataSet.Tables("customer").Columns("cid"), objDataSet.Tables("orders").Columns("cid"))
objDataSet.Relations.Add(objRel)
DataGrid1.DataSource = objDataSet.Tables("customer")

40. DataTable’s Rows Property
This is a collection of all the records in a table, a collection of DataRow objects.
DataRow object’s properties and methods.

41. Accessing a Record with Index
objAdapter.Fill(objDataSet, "Customer")
TextBox1.Text = objDataSet.Tables("Customer").Rows(rowIndex).Item(0)
TextBox2.Text = objDataSet.Tables("Customer").Rows(rowIndex).Item(1)

42. Access Rows in a DataRow Collection
dim objTable as DataTable = objDataset.Tables("Customer")
dim objRow as DataRow
For each objRow in objTable.Rows
strResult=strResult+“ " & objRow("cid") & " " & objRow("cname") & vbCrLf
Next

43. DataRow object’s GetChildRows Method
Returns a collection of rows from another table that are related as child rows to this row.

44. Displaying Parent/Child Records in a Relation
Define the relation.
Specify the relation in the GetChildRows method of the DataRow object.

45. Imports System.Data.OleDb
Public Class Form1
Inherits System.Windows.Forms.Form
Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Dim objConn As New OledbConnection(strConn)
Dim strSQLCust As String = "select * from customer;"
Dim strSQLOrder As String = "select * from orders;"
Dim objComm As New OledbCommand()
Dim objAdapter As New OledbDataAdapter()
Dim objDataSet As New DataSet()
Dim objRel As DataRelation
Dim strResult As String
Dim rowIndex As Integer = 0
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
objComm.Connection = objConn
objComm.CommandType = CommandType.Text
objComm.CommandText = strSQLCust
objAdapter.SelectCommand = objComm
objConn.Open()
objAdapter.Fill(objDataSet, "Customer")
objComm.CommandText = strSQLOrder
objAdapter.Fill(objDataSet, "Orders")
objRel = New DataRelation("custOrder", objDataSet.Tables("Customer").Columns("cid"), objDataSet.Tables("Orders").Columns("cid"))
objDataSet.Relations.Add(objRel)
Call showChild(rowIndex)
End Sub

46. Private Sub showChild(ByVal RowIndex)
TextBox1.Text = objDataSet.Tables("customer").Rows(RowIndex).Item("cid")
TextBox1.Text = objDataSet.Tables("customer").Rows(RowIndex).Item("cname")
Dim objOrderRel As DataRelation = objDataSet.Tables("customer").ChildRelations("custOrder")
Dim strResult As String
Dim objChildRow As DataRow
For Each objChildRow In objDataSet.Tables("customer").Rows(RowIndex).GetChildRows(objOrderRel)
strResult = strResult + objChildRow("oid") + " " + objChildRow("odate") + vbCrLf
Next
TextBox3.Text = strResult
End Sub
****Note****: How to prevent EOF error?
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
rowIndex += 1
Call showChild(rowIndex)

47. Display Child Records in Grid
This technique uses the fact that the DataView of a table can be used as a DataSource in binding a data grid.
Assuming a Customer/Orders relationship, for each customer record:
Use Table object’s Clone method to create a temporary child table structure.
Use Table object’s ImportRow method to import child records to the clone table.
Use the clone table’s DefaultView to bind the DataGrid.

48. Dim objRow As DataRow
Dim drFound As DataRow
drFound = objDataSet.Tables("Customer").Rows("0")
TextBox1.Text = drFound.Item("cid")
TextBox2.Text = drFound.Item("cname")
Dim childTable As DataTable
childTable = objDataSet.Tables("orders").Clone
For Each objRow In drFound.GetChildRows(objOrderRel)
childTable.ImportRow(objRow)
Next
DataGrid1.DataSource = childTable.DefaultView

49. Creating Parameter Queries
1. Specify the parameters in the SQL statement.
Dim strSQLOrder As String = "select * from orders where cid= ?;"
2. Add the parameters to the Command Object’s Parameters collection.
objComm.Parameters.Add("?cid", OleDbType.VarChar)
3. Set parameter’s value.
objAdapter.SelectCommand.Parameters("?cid").Value = "1"

50. Parameter Query Example
Dim strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Dim objConn As New OleDbConnection(strConn)
objConn.Open()
Dim strSQLOrder As String = "select * from orders where cid= ?;"
Dim objComm As New OleDbCommand()
Dim objAdapter As New OleDbDataAdapter()
Dim objDataSet As New DataSet()
objComm.Connection = objConn
objComm.CommandType = CommandType.Text
objComm.CommandText = strSQLOrder
objComm.Parameters.Add("?cid", OleDbType.VarChar)
objAdapter.SelectCommand.Parameters("?cid").Value = "1"
objAdapter.Fill(objDataSet, "Orders")
DataGrid1.DataSource = objDataSet
DataGrid1.DataMember = "orders"

51. Can we use child table’s view to display child records in a grid?

52. Multiple Forms: Where to import the oledb, and where to create the oledb objects
Imports System.Data.OleDb
Module Module1
Public strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source = c:\sales2k.mdb"
Public objConn As New OleDbConnection(strConn)
Public strSQLCust As String = "select * from customer;"
Public strSQLOrder As String = "select * from orders;"
Public objComm As New OleDbCommand()
Public objAdapter As New OleDbDataAdapter()
Public objDataSet As New DataSet()
Public objRel As DataRelation
Public strResult As String
Public rowIndex As Integer = 0
Public ObjDataView As New DataView()
Public Sub main()
objComm.Connection = objConn
objComm.CommandType = CommandType.Text
objComm.CommandText = strSQLCust
objAdapter.SelectCommand = objComm
objConn.Open()
objAdapter.Fill(objDataSet, "Customer")
objComm.CommandText = strSQLOrder
objAdapter.Fill(objDataSet, "Orders")
End Sub
End Module

53. Create Web Data Form Using ADO.Net Programming Model
Demo:
Create ADO objects and bind them to a dataGrid.
DataView

54. Using ToolBox/Data to Define Ado.Net Objects
Connection: ToolBox/Data/OledbConnection
ConnectionString
Command: ToolBox/Data/OledbCommand
Connection
CommandType
CommandText

55. Using DBMS Views Create views (queries) with DBMS
Create commands to select records from views.