ADO.NET (Active Data Objects)

Transcription

1 CSC Rapid Application Development ADO.NET (Active Data Objects) Department of Statistics and Computer Science Faculty of Applied Science University of Sri Jayewardanepura

2 How it Works DBMS (SQL Server) SQLConnection SQLCommand UI (DataGrid) DataSet Like a cache of the DB SQLDataAdapter Responsible for updates Kasun@sjp.ac.lk 2

3 SqlConnection Imports System.Data.SqlClient Dim CN As SqlConnection CN = New SqlConnection( "Data Source=LCSServer\SQL2005Server; Initial Catalog=RADdb; User ID=user1;Password=pw1")

4 The Connection Class Imports System.Data.SqlClient Dim CN As New SqlConnection("Data Source = localhost;" & "Initial Catalog = Northwind; uid = user_name;" & "password = user_password") Data Source = \\PowerServer Data Source = " ; Initial Catalog = BooksDB; uid = xxx; password= xxx" Kasun@sjp.ac.lk 4

5 Try CN.Open() SqlConnection.. If CN.State = ConnectionState.Open Then MsgBox("Workstation " & CN.WorkstationId & " connected to database " & CN.Database & " on the " & CN.DataSource & " server") End If Catch ex As Exception MsgBox("FAILED TO OPEN CONNECTION TO DATABASE DUE TO THE FOLLOWING ERROR" & vbcrlf & ex.message) End Try If CN.State = ConnectionState.Open Then CN.Close()

6 SqlDataAdapter Dim DA As New SqlDataAdapter

7 SqlCommand - Select Dim sqlcmdselect As New SqlCommand DA.SelectCommand = sqlcmdselect DA.SelectCommand.CommandText = "select * from stu where no= " & 123 & DA.SelectCommand.Connection = CN DA.Fill(DS, Student") DataGridView1.DataSource = DS.Tables( Student")

8 DataSet Dim DS As New DataSet TextBox1.Text = DS.Tables( Student").Rows(0)("No")

9 Multiple tables in Dataset CN.Open() CMD = New SqlCommand( Select * from stu, CN) DA.SelectCommand = CMD DA.Fill( DS, "Table1") DA.SelectCommand.CommandText = Select * from exam DA.Fill( DS, "Table2") adapter.dispose() CMD.Dispose() CN.Close() Kasun@sjp.ac.lk 9

10 SqlDataReader Dim DR As SqlDataReader DR = DA.SelectCommand.ExecuteReader() Do While DR.Read() Loop ListBox1.Items.Add(DR("name")) DR.Close() Kasun@sjp.ac.lk 10

11 SqlDataReader.. 11

12 SqlCommand - AddNew Dim sqlcmdaddnew As New SqlCommand DA.InsertCommand = sqlcmdaddnew DA.InsertCommand.CommandText = "insert into stu(no, Name) values('as ','kamal' )" DA.InsertCommand.Connection = CN DA.InsertCommand.ExecuteNonQuery()

13 SqlCommand - Update Dim sqlcmdupdate As New SqlCommand DA.UpdateCommand = sqlcmdupdate DA.UpdateCommand.CommandText = "update stu set name= Saman' where no = '300 " DA.UpdateCommand.Connection = CN DA.UpdateCommand.ExecuteNonQuery()

14 SqlCommand - Delete Dim sqlcmddalete As New SqlCommand DA.DeleteCommand = sqlcmddalete DA.DeleteCommand.CommandText = "Delete from stu where no = " & 300 & DA.DeleteCommand.Connection = CN DA.DeleteCommand.ExecuteNonQuery()

15 Sorting the Rows with ORDER BY USE Northwind SELECT CompanyName, ContactName, Country, City FROM Customers ORDER BY Country, City 15

16 Working with Calculated Fields USE Northwind SELECT Orders.OrderID, [Order Details].ProductID, [Order Details].[Order Details].UnitPrice * [Order Details].Quantity * (1 - [Order Details].Discount) AS SubTotal FROM Orders INNER JOIN [Order Details] ON Orders.OrderID = [Order Details].OrderID Kasun@sjp.ac.lk 16

17 Calculating Aggregates USE Northwind SELECT COUNT(CustomerID) FROM Customers WHERE Country = Germany Kasun@sjp.ac.lk 17

18 SQL s common aggregate functions Function Returns COUNT() SUM() AVG() MIN() MAX() The number (count) of values in a specified column The sum of values in a specified column The average of the values in a specified column The smallest value in a specified column The largest value in a specified column Kasun@sjp.ac.lk 18

19 USE Northwind SELECT COUNT(*) FROM Customers USE Northwind SELECT SUM(Quantity) FROM [Order Details] WHERE ProductID = 11 Kasun@sjp.ac.lk 19

20 USE Northwind SELECT SUM(Quantity * UnitPrice * (1 - Discount)) FROM [Order Details] WHERE ProductID = 11 USE Northwind SELECT SUM(Quantity), SUM(Quantity * UnitPrice * (1 - Discount)) FROM [Order Details] WHERE ProductID = 11 Kasun@sjp.ac.lk 20

21 Using SQL Joins Left outer, or left, join Right outer, or right, join Full outer, or full, join Inner join 21

22 Left Joins USE pubs SELECT title, pub_name FROM titles LEFT JOIN publishers ON titles.pub_id = publishers.pub_id Kasun@sjp.ac.lk 22

23 Right Joins USE pubs SELECT title, pub_name FROM titles RIGHT JOIN publishers ON titles.pub_id = publishers.pub_id Kasun@sjp.ac.lk 23

24 Full Joins USE pubs SELECT title, pub_name FROM titles FULL JOIN publishers ON titles.pub_id = publishers.pub_id Kasun@sjp.ac.lk 24

25 Inner Joins USE pubs SELECT titles.title, publishers.pub_name FROM titles, publishers WHERE titles.pub_id = publishers.pub_id Kasun@sjp.ac.lk 25

26 Grouping Rows USE Northwind SELECT ProductID, SUM(Quantity * UnitPrice *(1 - Discount)) AS [Total Revenues] FROM [Order Details] GROUP BY ProductID ORDER BY ProductID Kasun@sjp.ac.lk 26

27 Limiting Groups with HAVING USE NORTHWIND SELECT ProductID, SUM(Quantity) FROM [Order Details] GROUP BY ProductID HAVING SUM(Quantity) >

28 ACTION QUERIES 28

29 Deleting Rows DELETE table_name WHERE criteria DELETE Orders WHERE OrderDate < 1/1/1998 USE Northwind DELETE [Order Details] WHERE (OrderID IN ( SELECT OrderID FROM Orders WHERE (OrderDate < 1/1/1998 ))) DELETE Orders WHERE OrderDate < 1/1/1998 Kasun@sjp.ac.lk 29

30 Inserting New Rows INSERT table_name (column_names) VALUES (values) INSERT Customers (CustomerID, CompanyName) VALUES ( FRYOG, Fruit & Yogurt ) INSERT INTO SelectedProducts SELECT * FROM Products WHERE CategoryID = 4 Kasun@sjp.ac.lk 30

31 Editing Existing Rows UPDATE table_name SET field1 = value1, field2 = value2,... WHERE criteria UPDATE Customers SET Country= United Kingdom WHERE Country = UK Kasun@sjp.ac.lk 31

32 SHA1 Hashing Dim pwd As String = "your password" Dim bt() As Byte = System.Text.Encoding.Unicode.GetBytes(pwd) Dim sha1 As SHA1 = sha1.create() Dim hashedpassword As Byte() = sha1.computehash( bt ) Console.WriteLine( System.Text.Encoding.ASCII.GetString ( hashedpassword ) ) Kasun@sjp.ac.lk 32

33 Reference Mastering VB.NET 2010 ebook WWW 33