Database connectivity through ADO.Net in VB2010 express - vb.net

Question

Can anyone give me the source code to add database connectivity in VB2010 express through ADO.Net. Including all the commands to add, update, delete, retrieve and modify the database fields. It would be really helpful if anyone can provide me with a small prototype working model with the source code.

Answer 1

ADO.NET is more or less SQL query based. So for CRUD (Create, Read, Update, Delete) Operations have a look at the SQL-Language (the query syntax might have some smalle differences depending on the database you're using).
The connection uses the specialized provider entities implementing the IDbConnection, IDbCommand, IDbDataAdapter, IDbDataParameter and IDbTransaction Interfaces from the System.Data Namespace.
There are different Database Providers (e.g. Microsoft SQL Server, Oracle, mySQl, OleDb, ODBC etc.). Some of them are natively supported by the .NET Framework (MSSQL=System.Data.SqlClient Namespace, OleDb=System.Data.OleDb, ODBC=System.Data.Odbc Namespace) while others must be added through external libraries (you can also write your own database provider if you like).
With the IDBCommand Objects (e.g. the System.Data.SqlClient.SqlCommand object) you can define your SQL Commands.
Here is a small sample snippet which might help:
Public Class Form1
Sub DBTest()
'** Values to store the database values in
Dim col1 As String = "", col2 As String = ""
'** Open a connection (change the connectionstring to an appropriate value
'** for your database or load it from a config file)
Using conn As New SqlClient.SqlConnection("YourConnectionString")
'** Open the connection
conn.Open()
'** Create a Command object
Using cmd As SqlClient.SqlCommand = conn.CreateCommand()
'** Set the command text (=> SQL Query)
cmd.CommandText = "SELECT ID, Col1, Col2 FROM YourTable WHERE ID = #ID"
'** Add parameters
cmd.Parameters.Add("#ID", SqlDbType.Int).Value = 100 '** Change to variable
'** Execute the value and get the reader object, since we are trying to
'** get a result from the query, for INSERT, UPDATE, DELETE use
'** "ExecuteNonQuery" method which returns an Integer
Using reader As SqlClient.SqlDataReader = cmd.ExecuteReader()
'** Check if the result has returned som results and read the first record
'** If you have multiple records execute the Read() method until it returns false
If reader.HasRows AndAlso reader.Read() Then
'** Read the values of the current columns
col1 = reader("col1")
col2 = reader("col2")
End If
End Using
End Using
Debug.Print("Col1={0},Col2={1}", col1, col2)
'** Close the connection
conn.Close()
End Using
End Sub
End Class