About Chris Expertise I can answer pretty much any question relating to VB.NET and its use in a Windows environment. I specialize in ASP.NET web development and MSSQL database access.
Experience I have over 5 years of industry experience using VB.NET and other .NET technologies for web and database development.
Education/Credentials I have some college education, but does it really matter in this field of work?
Expert: Chris Date: 8/22/2007 Subject: connection and split function
Question Hi
I am new to vb.net but i am a php developer
I want to make a little application for my shop so I need help regarding this
1-I need a class for connection of vb.net with sql server 2000 because I don’t want to make connections every time for all my forms and example how to use that class
2-i have two textbox one for user enter and second is read only first textbox consists of numeric value and a slash sign (/)so when user enter first value / second value then second value shows in 2nd read only textbox
For this purpose I use this code
Private Sub TextBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus
If TextBox1.Text <> "" Then
Dim strToSplit As String = TextBox1.Text
Dim arTemp() As String = Split(strToSplit, "/")
TextBox2.Text = arTemp(1)
End If
End Sub
But user only enter first value then it gives error how could I solve this problem and also how can I prevent for user to enter alphabetic and slash sign (/) twice
I am using visual studio.net 2003
I am very thankful to you
Regards,
Bilal
Answer As far as connections to SQL server go, you are supposed to open your connection just before you use it to execute a query, and close it immediately afterwards, to keep the server's connection pool from filling up. You can create a small class to encapsulate this functionality, as well as connection settings, and use it for all of your queries.
'--[ dbaccess.vb ]--
Imports System.Data.SqlClient
Public Class DBAccess
Protected m_strConnString As String = ""
Public ReadOnly Property ConnectionString() As String
Get
Return m_strConnString
End Get
End Property
Public Sub New(ByVal strConnString As String)
m_strConnString = strConnString
End Sub
' Prevent a new instance from being made without specifying a connection string
Private Sub New()
End Sub
Public Function MakeConnection() As SqlConnection
Return New SqlConnection(m_strConnString)
End Function
Public Function MakeCommand(ByVal strQuery As String) As SqlCommand
Return New SqlCommand(strQuery, MakeConnection())
End Function
End Class
'--[ end dbaccess.vb ]--
And to use it:
Dim objDBA As New DBAccess("initial catalog=DATABASE;data source=SERVER;user id=USER;password=PASS")
Dim objCMD As SqlCommand = objDBA.MakeCommand("SELECT * FROM Users")
objCMD.Connection.Open()
Dim objDR As SqlDataReader = objCMD.ExecuteReader()
'...
objCMD.Connection.Close()
This is a very simple implementation, it might be perfect for what you need, or it might not. You can also take a look at this project I made and have been using for all of my data access needs, I call it Table Assimilator: http://www.beyourown.net/areas/Developers/TableAssimilator.aspx
It's a free download, but you'll have to register first.
As for question #2... you're assuming that you'll have two entries in the array returned from the .Split() function. This won't be true if there's not yet a "/" character followed by some other text. You might also want to use the TextChanged event handler, to have TextBox2's value update as text is entered in TextBox1:
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
' it's faster to check the length of the string
If (TextBox1.Text.Length > 0) Then
' the c after "/" indicates its a character to split by, faster performance
Dim arTemp As String() = TextBox1.Text.Split("/"c)
' make sure there's two entries in the array we got from Split()
If (arTemp.Length > 1) Then
TextBox2.Text = arTemp(1)
End If
End If
End Sub
