Lecture 7

1. Select Operation 2. Insert Operation 3. Update Operation 4. Delete Operation

Dim connetionString As String Dim cnn As SqlConnection Dim cmd As SqlCommand Dim sql As String // var for command Dim reader As SqlDataReader connetionString = "Data Source=.\SqlExpress;Initial Catalog=my_database;Integrated Security=True“ sql = "select * from table_1“ cnn = New SqlConnection(connetionString) Try cnn.Open() cmd = New SqlCommand(sql, cnn) reader = cmd.ExecuteReader() While reader.Read() MsgBox(reader.Item(0) & " - " & reader.Item(1) & " - " & reader.Item(2)) End While reader.Close() cmd.Dispose() cnn.Close() Catch ex As Exception MsgBox("Can not open connection ! ") End Try

 The ExecuteReader method call is suitable when the underlying command object is set with the Select statement.  Select statement will return one or more records and those records are packed in SqlDataReader by the ExecuteReader method and then returned to the caller.  cmd.Dispose()  Dispose releases all the resources used by the object.

 SQL Adapter:  Initializes a new instance of the SqlDataAdapter class with a SelectCommand and a SqlConnection object.  Provides the communication between the Dataset and the Datasource.  That is the DataAdapter uses the Select statements to fill a DataSet ▪ and  use the other three SQL commands (Insert, Update, delete) to transmit changes back to the Database.

 Dim connetionString As String  Dim connection As SqlConnection  Dim adapter As New SqlDataAdapter  Dim sql As String  connetionString = "Data Source=.\SqlExpress;Initial Catalog=my_database;Integrated Security=True“  connection = New SqlConnection(connetionString)  sql = "insert into table_1 (id,name,batch) values(3,'Babar','2k13')“  Try  connection.Open()  adapter.InsertCommand = New SqlCommand(sql, connection)  adapter.InsertCommand.ExecuteNonQuery()  MsgBox("Row inserted !! ")  Catch ex As Exception ▪ MsgBox(ex.ToString)  End Try

 Dim connetionString As String  Dim connection As SqlConnection  Dim adapter As New SqlDataAdapter  Dim sql As String  connetionString = "Data Source=.\SqlExpress;Initial Catalog=my_database;Integrated Security=True"  connection = New SqlConnection(connetionString)  sql = "update table_1 set name = 'zeeshan' where id = 3“  Try  connection.Open()  adapter.UpdateCommand = connection.CreateCommand  adapter.UpdateCommand.CommandText = sql  adapter.UpdateCommand.ExecuteNonQuery()  MsgBox("Row updated !! ")  Catch ex As Exception  MsgBox(ex.ToString)  End Try

 Dim connetionString As String  Dim connection As SqlConnection  Dim adapter As New SqlDataAdapter  Dim sql As String  connetionString = "Data Source=.\SqlExpress;Initial Catalog=my_database;Integrated Security=True“  connection = New SqlConnection(connetionString)  sql = "delete table_1 where id =4“  Try  connection.Open()  adapter.DeleteCommand = connection.CreateCommand  adapter.DeleteCommand.CommandText = sql  adapter.DeleteCommand.ExecuteNonQuery()  MsgBox("Row(s) deleted !! ")  Catch ex As Exception  MsgBox(ex.ToString)  End Try

Assignment: Write a calculator program in VB.Net. Assignment: Create web browser program with back button. Assignment: Write short description of VB.net controls covered in class (Handwritten). Assignment: What are advantages of VB.net in comparison with Visual Basic 6? Assignment: Create a database of your class and retrieve it on Gridview.