Why i am getting ERROR [HY000] parameter marker count incorrect.
I am using SQLite3 Odbc Driver on my VB.Net Project and here's my code structure.
On my DBClass
Imports System.Data.Odbc
Public Class DbClass
Private DbConnection As New OdbcConnection("DRIVER=SQLite3 ODBC Driver;Database=E:\VB.NET Projects\MyBeDb.db;LongNames=0;Timeout=1000;NoTXN=0; SyncPragma=NORMAL;StepAPI=0;")
Private DbCommand As New OdbcCommand
Private DbDataAdapter As New OdbcDataAdapter
Private DbParameter As New List(Of OdbcParameter)
Private DbRecordCount As Integer = 0
Private DbDataTable As DataTable
Sub ExecuteQuery(_Query As String)
DbRecordCount = 0
DbConnection.Open()
DbCommand = New OdbcCommand(_Query, DbConnection)
DbParameter.ForEach(Sub(p) DbCommand.Parameters.Add(p))
DbParameter.Clear()
DbDataTable = New DataTable
DbDataAdapter = New OdbcDataAdapter(DbCommand)
DbRecordCount = DbDataAdapter.Fill(DbDataTable)
If DbConnection.State = ConnectionState.Open Then DbConnection.Close()
End Sub
Sub AddParameters(_Name As String, _Value As Object)
Dim NewParam As New OdbcParameter(_Name, _Value)
DbParameter.Add(NewParam)
End Sub
Sub Authenticate(_Username As String, _Password As String)
AddParameters("Un", _Username)
AddParameters("Pw", _Password)
ExecuteQuery("SELECT * FROM UserAccounts WHERE [Username] LIKE #Un AND [Password] LIKE #Pw;")
End Sub
End Class
On Button Click
Private myDb As New DbClass
Private Sub Login_Click(sender As Object, e As EventArgs) Handles Login.Click
Try
myDb.Authenticate("Admin", "Password")
Catch ex As Exception
MsgBox(ex.Message & Environment.NewLine & Environment.NewLine & ex.StackTrace)
End Try
End Sub
I tried using ? instead of # and it didn't throw any exception message if i mistype a username and password.
Related
The following code is supposed to display information from a database but there is an error (the title of this question) on the DBCmd.ExecuteNonQuery() line of code.
Does anyone know how I can resolve this problem?
• I am using VB.NET
• I am using an Access database
The code is:
Imports System.Data.OleDb
Public Class frmCheckAvailablity
Private DBCon As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;" &
"Data Source=|DataDirectory|\NewHotel.mdb;")
Private Access As New DBControl
Dim QRY As String
Private DBCmd As OleDbCommand
Dim DBDR As OleDbDataReader
Public DBDA As New OleDbDataAdapter("SELECT RoomType FROM tblRoomBookings", DBCon)
Public DT As New DataTable
Public DS As New DataSet
Public DR As DataRow
Private Function NotEmpty(text As String) As Boolean
Return Not String.IsNullOrEmpty(text)
End Function
Private Sub frmCheckAvailability_Shown(sender As Object, e As EventArgs) Handles Me.Shown
'RUN QUERY
Access.ExecQuery("SELECT * FROM tblRoomBookings ORDER BY BookingID ASC")
If NotEmpty(Access.Exception) Then MsgBox(Access.Exception) : Exit Sub
End Sub
Private Sub frmCheckAvailability_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'NewHotelDataSet.tblRoomBookings' table. You can move, or remove it, as needed.
Me.TblRoomBookingsTableAdapter.Fill(Me.NewHotelDataSet.tblRoomBookings)
If DBCon.State = ConnectionState.Closed Then DBCon.Open() : Exit Sub
End Sub
Private Sub Search()
DBDA.Fill(DT)
txtSearch.AutoCompleteCustomSource.Clear()
For Each DBDR In DT.Rows
txtSearch.AutoCompleteCustomSource.Add(DBDR.Item(0).ToString)
Next
txtSearch.AutoCompleteMode = AutoCompleteMode.SuggestAppend
txtSearch.AutoCompleteSource = AutoCompleteSource.CustomSource
End Sub
Private Sub SearchCustomers(RoomType As String)
'ADD PARAMETERS & RUN QUERY
Access.AddParam("#RoomType", "%" & RoomType & "%")
Access.ExecQuery("SELECT * FROM tblRoomBookings WHERE RoomType LIKE #RoomType")
'REPORT & ABORT ON ERRORS
If NotEmpty(Access.Exception) Then MsgBox(Access.Exception) : Exit Sub
End Sub
Private Sub txtSearch_TextChanged(sender As Object, e As EventArgs) Handles txtSearch.TextChanged
QRY = "SELECT FullName FROM tblRoomBookings WHERE RoomType'" & txtSearch.Text & "'"
DBCmd = New OleDbCommand(QRY, DBCon)
DBCmd.ExecuteNonQuery()
DBDR = DBCmd.ExecuteReader
If DBDR.Read Then
txtRoomType.Text = DBDR("RoomType")
txtFirstNight.Text = DBDR("FirstNight")
txtLastNight.Text = DBDR("LastNight")
txtNoNights.Text = DBDR("NoNights")
End If
End Sub
The only place in the code that I see DBcmd.ExecuteNonQuery is in search text changed event. Do really want to run this code every time the users types a letter?
Do not create a new connection at the class (Form) level. Every time the connection is used it needs to be disposed so it can be returned to the connection pool. Using...End Using blocks handle this for you even if there is an error.
Don't call .ExecuteNonQuery. This is not a non query; it begins with Select.
You can't execute a command without an Open connection.
Never concatenate strings for sql statments. Always use parameters.
The connection is open while the reader is active. Don't update the user interface while the connection is open.
Load a DataTable and return that to the user interface code where you update the user interface.
Private ConStr As String = "Your connection string"
Private Function GetSearchResults(Search As String) As DataTable
Dim dt As New DataTable
Dim QRY = "SELECT FullName FROM tblRoomBookings WHERE RoomType = #Search"
Using DBcon As New OleDbConnection(ConStr),
DBCmd As New OleDbCommand(QRY, DBcon)
DBCmd.Parameters.Add("#Search", OleDbType.VarChar).Value = Search
DBcon.Open()
Using reader = DBCmd.ExecuteReader
dt.Load(reader)
End Using
End Using
Return dt
End Function
Private Sub txtSearch_TextChanged(sender As Object, e As EventArgs) Handles txtSearch.TextChanged
Dim dtSearch = GetSearchResults(txtSearch.Text)
If dtSearch.Rows.Count > 0 Then
txtRoomType.Text = dtSearch(0)("RoomType").ToString
txtFirstNight.Text = dtSearch(0)("FirstNight").ToString
txtLastNight.Text = dtSearch(0)("LastNight").ToString
txtNoNights.Text = dtSearch(0)("NoNights").ToString
End If
End Sub
Imports System.Data.SqlClient
Public Class SQLCONTROL
Private DBcon As New SqlConnection("Data Source=DESKTOP-DQ7NOIF\SQLEXPRESS;Integrated Security=True")
Private DBcom As New SqlCommand
Public DBDA As SqlDataAdapter
Public DBDT As DataTable
Public Params As New List(Of SqlParameter)
Public RecordCount As Integer
Public Exception As String
Public Sub New()
End Sub
Public Sub New(ConnctionString As String)
DBcon = New SqlConnection(ConnctionString)
End Sub
Public Sub ExecQuery(Query As String)
RecordCount = 0
Exception = ""
Try
DBcon.Open()
DBcom = New SqlCommand(Query, DBcon)
Params.ForEach(Sub(p) DBcom.Parameters.Add(p))
DBDT = New DataTable
DBDA = New SqlDataAdapter(DBcom)
RecordCount = DBDA.Fill(DBDT)
Catch ex As Exception
Exception = "ExecQuery Error" & vbNewLine & ex.Message
Finally
If DBcon.State = ConnectionState.Open Then DBcon.Close()
End Try
End Sub
Public Sub AddParam(Name As String, Value As Object)
Dim NewParam As New SqlParameter(Name, Value)
Params.Add(NewParam)
End Sub
Public Function HasException(Optional Report As Boolean = False) As Boolean
If String.IsNullOrEmpty(Exception) Then Return False
If Report = True Then MsgBox(Exception, MsgBoxStyle.Critical, "Exception:")
Return True
End Function
End Class
the exception message is "A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
Additional information: Nom d'objet 'Utilisateurs' non valide."
thanks
Many database objects (including connections and commands) expose a .Dispose method which means that they may be using unmanaged resources which need to be released. To guarantee that .Dispose is called .net provides Using...End Using.
Any errors will bubble up to the calling code where you can handle them and inform the user. After all, your class could be used in a web app or phone app where MsgBox would not work. Leave informing the user to the User Interface code.
Public Class SQLCONTROL
Private ConStr As String = "Data Source=DESKTOP-DQ7NOIF\SQLEXPRESS;Integrated Security=True"
Public Function IsUserValid(userName As String, password As String) As Boolean
Dim RetVal As Integer
Using DBcon As New SqlConnection(ConStr),
DBcom As New SqlCommand("Select Count(*) From [Utilisateurs] Where UserName = #UserName And Password = #Password;", DBcon)
DBcom.Parameters.Add("#UserName", SqlDbType.NVarChar, 50).Value = userName
DBcom.Parameters.Add("#Password", SqlDbType.NVarChar, 100).Value = password
DBcon.Open()
RetVal = CInt(DBcom.ExecuteScalar)
End Using
If RetVal = 0 Then
Return False
End If
Return True
End Function
'To return a DataTable for a DataGridView
Public Function GetCustomerOrders(Customer As String) As DataTable
Dim dt As New DataTable
Using DBcon As New SqlConnection(ConStr),
DBcom As New SqlCommand("Select * From Orders Where CustomerName = #CustomerName;", DBcon)
DBcom.Parameters.Add("#CustomerName", SqlDbType.NVarChar, 100).Value = Customer
DBcon.Open()
dt.Load(DBcom.ExecuteReader)
End Using
Return dt
End Function
End Class
Usage in Form
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim sql As New SQLCONTROL
If sql.IsUserValid("Mary", "MySecretPassword") Then
'Do something
End If
End Sub
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
Dim sql As New SQLCONTROL
DataGridView1.DataSource = sql.GetCustomerOrders("General Motors")
End Sub
Naturally, I only guessed at field names, types, and sizes. Check your database.
In a real application you would never store passwords as plain text.
I am trying to edit customers using my C# project to learn how to implement this code in VB.net. The project was successful in adding customers, but when it got to editing customers, things got a bit more complicated because I needed to get the id of the row selected and pass it to a string. I have the MainForm.vb which could open CustomerForm.vb when I click on 'Edit'. When CustomerForm.vb opens, it failed to show the customer's info. I am not sure if FillDataTable() function is necassary, I would like to know if there is an improvement to this.
CustomerForm.vb
Imports System.Data.SqlClient
Public Class CustomerForm
Private objConnection As SqlConnection
Public objDataTable As DataTable = New DataTable()
Public objSqlCommand As SqlCommand = New SqlCommand()
Public editMode As Boolean = False
Public id As String = ""
Public FName As String = ""
Public LName As String = ""
Public PhNumber As String = ""
Public ReadOnly Property Connection As SqlConnection
Get
Return Me.objConnection
End Get
End Property
Dim CS As String = ("server=CASHAMERICA;Trusted_Connection=yes;database=ProductsDatabase2; connection timeout=30")
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
Try
If editMode = False Then
If txtFirstName.Text = "" Then
MessageBox.Show("First Name Is required")
ElseIf txtLastName.Text = "" Then
MessageBox.Show("Last Name Is required")
Else
Dim con As New SqlConnection(CS)
con.Open()
Dim cmd As New SqlCommand("INSERT INTO Customers(FIrstName,LastName,PhoneNumber) VALUES(#FName, #LName, #PhNumber)", con)
cmd.Parameters.AddWithValue("#FName", txtFirstName.Text)
cmd.Parameters.AddWithValue("#LName", txtLastName.Text)
cmd.Parameters.AddWithValue("#PhNumber", txtPhoneNumber.Text)
cmd.ExecuteNonQuery()
MessageBox.Show("Customer has been added!")
con.Close()
End If
ElseIf editMode = True Then
If txtFirstName.Text = "" Then
MessageBox.Show("First Name Is required")
ElseIf txtLastName.Text = "" Then
MessageBox.Show("Last Name Is required")
Else
Dim con As New SqlConnection(CS)
con.Open()
Dim cmd As New SqlCommand("UPDATE Customers SET FIrstName = #FName, LastName = #LName, PhoneNumber = #PhNumber WHERE Id = #Id", con)
cmd.Parameters.AddWithValue("#Id", id)
cmd.Parameters.AddWithValue("#FName", txtFirstName.Text)
cmd.Parameters.AddWithValue("#LName", txtLastName.Text)
cmd.Parameters.AddWithValue("#PhNumber", txtPhoneNumber.Text)
cmd.ExecuteNonQuery()
MessageBox.Show("Customer has been edited.")
con.Close()
End If
End If
Catch ex As Exception
MessageBox.Show(Me, ex.Message, "Save Failed", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End Sub
Private Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click
Me.Close()
End Sub
Private Sub CustomerForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
If editMode = False Then
GetId()
Else
textId.Text = id
txtFirstName.Text = FName
txtLastName.Text = LName
txtPhoneNumber.Text = PhNumber
End If
End Sub
Private Sub GetId()
Dim con As New SqlConnection(CS)
con.Open()
Dim cmd As New SqlCommand("SELECT MAX(id)+1 FROM Customers")
textId.Text = FillDataTable().Rows(0)(0).ToString()
If textId.Text = "" Then
textId.Text = "1"
End If
End Sub
Public Property CommandText As String
Get
Return CommandText
End Get
Set(ByVal value As String)
CommandText = value
End Set
End Property
Public Sub OpenDBConnection()
objConnection = New SqlConnection(CS)
objConnection.Open()
End Sub
Public Sub CreateCommandObject()
objSqlCommand = objConnection.CreateCommand()
objSqlCommand.CommandText = CommandText
objSqlCommand.CommandType = CommandType.Text
End Sub
Public Function FillDataTable() As DataTable
objDataTable = New DataTable()
objSqlCommand.CommandText = CommandText
objSqlCommand.Connection = objConnection
objSqlCommand.CommandType = CommandType.Text
objDataTable.Load(objSqlCommand.ExecuteReader())
objConnection.Close()
Return objDataTable
End Function
Public Sub CloseConnection()
If objConnection IsNot Nothing Then objConnection.Close()
End Sub
End Class
MainForm.vb
Imports System.Windows.Forms.LinkLabel
Public Class MainForm
Private Sub ExitToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ExitToolStripMenuItem.Click
Me.Close()
End Sub
Private Sub AddToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles AddToolStripMenuItem.Click
CustomerForm.ShowDialog()
End Sub
Private Sub AddToolStripMenuItem1_Click(sender As Object, e As EventArgs) Handles AddToolStripMenuItem1.Click
ProductForm.ShowDialog()
End Sub
Private Sub ViewProductsToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ViewProductsToolStripMenuItem.Click
ManageProductsForm.ShowDialog()
End Sub
Private Sub AboutToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles AboutToolStripMenuItem.Click
AboutForm.Show()
End Sub
Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'ProductsDatabase2DataSet1.Customers' table. You can move, or remove it, as needed.
Me.CustomersTableAdapter.Fill(Me.ProductsDatabase2DataSet1.Customers)
End Sub
Private Sub gridCustomers_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles gridCustomers.MouseUp
Try
Dim f As CustomerForm = New CustomerForm()
f.editMode = True
Dim rowIndex As Integer = gridCustomers.CurrentCell.RowIndex
f.id = gridCustomers.Rows(rowIndex).Cells("colId").Value.ToString()
f.FName = gridCustomers.Rows(rowIndex).Cells("colFirstName").Value.ToString()
f.LName = gridCustomers.Rows(rowIndex).Cells("colLastName").Value.ToString()
f.PhNumber = gridCustomers.Rows(rowIndex).Cells("colPhoneNumber").Value.ToString()
f.Show()
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
Private Sub gridCustomers_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles gridCustomers.CellContentClick
Dim f As CustomerForm = New CustomerForm()
f.ShowDialog(Me)
f.editMode = True
End Sub
End Class
Error Message:
Customer Info not displayed:
As mentioned, it seems like you have several things potentially going on.
The first thing I would change is your public sql objects. You don't need them to be public. It also increases the chances for issues if you're using the same objects in multiple places.
SqlCommand, SqlConnection, and SqlDataAdapters can be immediately disposed of (in most cases) as soon as they are used.
One easy method to handling all of that is to throw everything inside of a USING block.
Dim sqlResult As New Datatable()
Using cn As New SqlConnection("Connection String here"),
cmd As New SqlCommand(sql, cn),
adapt As New SqlDataAdapter(cmd)
cn.Open()
'Handle stored procedure vs select options
If sql.Contains("SELECT") Then
cmd.CommandType = CommandType.Text
Else
cmd.CommandType = CommandType.StoredProcedure
End If
'If parameters passed, else comment out
cmd.Parameters.AddWithValue("#parameterName", parameterValue)
sqlResult = New DataTable(cmd.CommandText)
adapt.Fill(sqlResult)
End Using
Now all your objects are disposed of as soon as your datatable is filled.
*This example uses a datatable, but it is the same idea for anything interacting with sql objects.
If implemented, you may find out that some objects weren't being disposed of or initialized properly.
Another method for testing where things are going wrong is to query the states of the SQL objects before or around the error to see if something isn't set correctly or is uninitialized.
With this line of code
using (rdr as mysqldatareader = cmd.executereader())
I get an error saying rdr is not declared. When I remove the brackets so that it becomes
Using rdr As MySqlDataReader = cmd.ExecuteReader()
I get error on this line tmpObj.No = rdr("No").ToString()saying No is not a member of the project.Form.Appdata and this line
tmpObj.Template = templa8 and Template is not a member of the project.Form.AppData. Note that I have already put this: Private FPList As New List(Of AppData) at the class level, as a member. Definitely I'm doing something wrong. Any suggestions?
'THIS NEEDS TO BE AT THE CLASS-LEVEL, AS A MEMBER
'Private FPList As New List(Of AppData)
Public Class AppData
Public Sub Update()
RaiseEvent OnChange()
End Sub
Public Event OnChange()
Public FPList As New List(Of AppData)
Public IsEventHandlerSucceeds As Boolean = True
Public IsFeatureSetMatched As Boolean = False
Public FalseAcceptRate As Integer = 0
Public Sub Update()
RaiseEvent OnChange()
End Sub
Public Event OnChange()
Public FPList As New List(Of AppData)
End Class
Private Sub Me_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles MyBase.Load
Init()
StartCapture()
Dim sql As String = "SELECT * FROM new_case_file"
Using conn As New MySqlConnection("**** "), _
cmd As New MySqlCommand(sql, conn)
conn.Open()
Using (rdr As MySqlDataReader = cmd.ExecuteReader())
FPList.Clear()
While (rdr.Read())
Dim tmpObj As New AppData
tmpObj.No = rdr("No").ToString()
Dim fpBytes As Byte() = rdr("FingerPrint")
Using MemStream As New IO.MemoryStream(fpBytes)
Dim templa8 As New DPFP.Template()
templa8.DeSerialize(MemStream)
tmpObj.Template = templa8
End Using
FPList.Add(tmpObj)
End While
rdr.Close()
End Using
End Using
End Sub
You correct that error by adding the following to your AppData class
Private _No As String
Public Property No As String
Get
Return _No
End Get
Set(value as String)
_No = value
End Set
End Property
Private _Template As DPFP.Template
Public Property Template As DPFP.Template
Get
Return _Template
End Get
Set(value as DPFP.Template)
_Template = value
End Set
End Property
but that will not necessarily make your code work.
I am writing a small postIt programm which should enable the user to send little notes to other computers using a database.
I have a main-Form where I can write messages and see users online, a sheet-form which should display messages and a sql database which has a table for users and messages.
The idea is that I am writing messages into the Messagestable and my programm uses SqlDependency to get the new messages and to show them in sheets. So far so good.
The problem is when I add a new Message to my table the SqlDependency fires an Event and my mainForm creates a new sheet which freezes after sheet.Show() is called. The mainForm keeps on running but my sheets always do not respond.
Here's my code:
DBListener:
Imports System.Data
Imports System.Data.Sql
Imports System.Data.SqlClient
Imports System.Threading
Public Class DBListener
Private changeCount As Integer = 0
Private Const tableName As String = "IMSMessages"
Private Const statusMessage As String = _
"{0} changes have occurred."
Private exitRequested As Boolean = False
Private waitInProgress As Boolean = False
Private recieverHost As String
Private imsMain As IMSMain
Public Sub New(main As IMSMain, recieverHost As String)
Me.imsMain = main
Me.recieverHost = recieverHost
initCommand(recieverHost)
SqlDependency.Start(connectionString)
GetMsg(recieverHost)
End Sub
Private connectionString As String = "Data Source=NB_RANDY\SQLEXPRESS;Initial Catalog=eurom_test;Integrated Security=SSPI;"
Private sqlConn As SqlConnection = New SqlConnection(connectionString)
Private commandMesg As SqlCommand = Nothing
Private commandUsers As SqlCommand = Nothing
Private Sub initCommand(recieverHost As String)
commandMesg = New SqlCommand
commandMesg.CommandText = "SELECT MessageID,SenderHost,RecieverHost,isRead,isRecieved,Stamp from dbo.IMSMessages " &
"WHERE RecieverHost=#RecieverHost" &
" AND isRecieved = 0"
commandMesg.Parameters.Add("#RecieverHost", SqlDbType.VarChar).Value = recieverHost
commandMesg.Connection = sqlConn
commandUsers = New SqlCommand
commandUsers.CommandText = "Select HostName From dbo.IMSUser"
End Sub
Private Sub OnChangeMsg(ByVal sender As System.Object, ByVal e As System.Data.SqlClient.SqlNotificationEventArgs)
Dim dep As SqlDependency = DirectCast(sender, SqlDependency)
RemoveHandler dep.OnChange, AddressOf OnChangeMsg
GetMsg(recieverHost)
End Sub
Private Sub OnChangeUser(ByVal sender As System.Object, ByVal e As System.Data.SqlClient.SqlNotificationEventArgs)
Dim dep As SqlDependency = DirectCast(sender, SqlDependency)
RemoveHandler dep.OnChange, AddressOf OnChangeUser
GetUsers()
End Sub
Public Sub GetMsg(recieverHost As String)
If Not sqlConn.State = ConnectionState.Open Then
sqlConn.Open()
End If
commandMesg.Notification = Nothing
Dim dep As SqlDependency = New SqlDependency(commandMesg)
AddHandler dep.OnChange, New OnChangeEventHandler(AddressOf OnChangeMsg)
Dim table As DataTable = New DataTable
Dim adapter As SqlDataAdapter = New SqlDataAdapter(commandMesg)
adapter.Fill(table)
imsMain.recieveNewMessages(table)
End Sub
Public Sub GetUsers()
If Not sqlConn.State = ConnectionState.Open Then
sqlConn.Open()
End If
commandMesg.Notification = Nothing
Dim dep As SqlDependency = New SqlDependency(commandUsers)
AddHandler dep.OnChange, New OnChangeEventHandler(AddressOf OnChangeUser)
Dim table As DataTable = New DataTable
imsMain.updateOnlineUserList()
End Sub
End Class
IMSMain-Form:
Imports System.Data.SqlClient
Imports System.Threading
Public Class IMSMain
Private user As IMSUser
Private listener As DBListener
Private sqlConn As SqlConnection
Public Sub New()
InitializeComponent()
sqlConn = New SqlConnection("Data Source=NB_RANDY\SQLEXPRESS;Initial Catalog=eurom_test;Integrated Security=SSPI;")
Me.user = New IMSUser(My.Computer.Name)
user.register()
updateOnlineUserList()
listener = New DBListener(Me, user.HostName)
End Sub
Private Sub onSend(sender As Object, e As EventArgs) Handles bt_send.Click
Dim command As SqlCommand = New SqlCommand
Dim msgText = tb_text.Text
Dim reciever As IMSUser = lb_Online.SelectedItem
Dim insert_string As String = "Insert INTO dbo.IMSMessages(Text,RecieverHost,SenderHost,isRead,isRecieved,Stamp) Values(#Text,#RecieverHost,#SenderHost,#isRead,#isRecieved,#Stamp)"
Dim adapter As SqlDataAdapter = New SqlDataAdapter
Dim table As DataTable = New DataTable()
Try
If Not sqlConn.State = ConnectionState.Open Then
sqlConn.Open()
End If
command.Connection = sqlConn
command.CommandText = insert_string
adapter.SelectCommand = command
adapter.Fill(table)
command.CommandText = insert_string
command.Parameters.Add("#Text", SqlDbType.VarChar).Value = msgText
command.Parameters.Add("#RecieverHost", SqlDbType.NChar).Value = reciever.HostName
command.Parameters.Add("#SenderHost", SqlDbType.NChar).Value = user.HostName
command.Parameters.Add("#isRecieved", SqlDbType.Bit).Value = 0
command.Parameters.Add("#isRead", SqlDbType.Bit).Value = 0
command.Parameters.Add("#Stamp", SqlDbType.SmallDateTime).Value = DateTime.Now
command.ExecuteNonQuery()
Catch ex As Exception
Console.WriteLine("onSend: internal database exception" + ex.Message)
End Try
End Sub
Private Sub processMessageId(refMessageID As Integer)
Dim command As SqlCommand = New SqlCommand
Dim msgID_string As String = "SELECT * from dbo.IMSMessages " &
"WHERE MessageID=#MessageID AND isRecieved = 0" &
" ORDER BY Stamp"
Dim isRecievedUpdate_string As String = "Update dbo.IMSMessages " &
"SET isRecieved=1" &
" WHERE MessageID=#MessageID"
Dim adapter As SqlDataAdapter = New SqlDataAdapter
Dim table As DataTable = New DataTable()
Try
If Not sqlConn.State = ConnectionState.Open Then
sqlConn.Open()
End If
command = New SqlCommand
command.CommandText = msgID_string
command.Parameters.Add("#MessageID", SqlDbType.Int).Value = refMessageID
command.Connection = sqlConn
adapter.SelectCommand = command
adapter.Fill(table)
command = New SqlCommand
command.Connection = sqlConn
command.CommandText = isRecievedUpdate_string
command.Parameters.Add("#MessageID", SqlDbType.Int).Value = refMessageID
command.ExecuteNonQuery()
Catch ex As Exception
Console.WriteLine("processMessageID: internal database exception" + ex.Message)
End Try
Try
Dim row As DataRow = table.Rows(0)
Dim senderHost As String = row("SenderHost")
Dim sender As IMSUser = New IMSUser(senderHost)
Dim currentSheet As IMSSheet
Dim stringText As String = row("Text")
Dim stamp As Date = row("Stamp")
currentSheet = New IMSSheet(sender, stringText, stamp)
currentSheet.Show()
Catch ex As Exception
Console.WriteLine("processMessageID: error while showing sheet")
End Try
End Sub
Public Sub recieveNewMessages(newMessageTable As DataTable)
For Each row As DataRow In newMessageTable.Rows
Dim id As Integer = row("MessageID")
processMessageId(id)
Next
End Sub
Public Sub updateOnlineUserList()
lb_Online.Items.Clear()
Dim adapter As SqlDataAdapter = New SqlDataAdapter
Dim table As DataTable = New DataTable()
Dim command As SqlCommand = New SqlCommand
Dim onlineUser_string = "Select * FROM dbo.IMSUser"
command.CommandText = onlineUser_string
Try
If Not sqlConn.State = ConnectionState.Open Then
sqlConn.Open()
End If
command.Connection = sqlConn
adapter.SelectCommand = command
adapter.Fill(table)
Catch ex As Exception
Console.WriteLine("internal database exception" + ex.Message)
End Try
For Each row As DataRow In table.Rows
Dim tmp As IMSUser = New IMSUser(row("HostName"))
If Not user.Equals(tmp) Then
lb_Online.Items.Add(tmp)
End If
Next
End Sub
End Class
IMSSheet-Form:
Public Class IMSSheet
Dim IsDraggingForm As Boolean = False
Private MousePos As New System.Drawing.Point(0, 0)
Public Sub New(session As IMSUser, text As String, stamp As Date)
Ini
tializeComponent()
Me.tb_sender.Text = session.HostName
addText(text, stamp)
End Sub
Private Sub addText(msg As String, stamp As DateTime)
Dim currentText As String = tb_text.Text
currentText = currentText + stamp.ToString + Environment.NewLine + msg + Environment.NewLine
tb_text.Text = currentText
End Sub
Private Sub IMSSheet_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) Handles MyBase.MouseDown
If e.Button = MouseButtons.Left Then
IsDraggingForm = True
MousePos = e.Location
End If
End Sub
Private Sub IMSSheet_MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs) Handles MyBase.MouseUp
If e.Button = MouseButtons.Left Then IsDraggingForm = False
End Sub
Private Sub IMSSheet_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles MyBase.MouseMove
If IsDraggingForm Then
Dim temp As Point = New Point(Me.Location + (e.Location - MousePos))
Me.Location = temp
temp = Nothing
End If
End Sub
Private Sub onClose(sender As Object, e As EventArgs) Handles bt_Close.Click
Me.Close()
End Sub
Private Sub bt_minimize_Click(sender As Object, e As EventArgs) Handles bt_minimize.Click
Me.WindowState = FormWindowState.Minimized
End Sub
Private Sub bt_Close_MouseHover(sender As Object, e As EventArgs) Handles bt_Close.MouseHover
End Sub
Private Sub bt_minimize_MouseHover(sender As Object, e As EventArgs) Handles bt_minimize.MouseHover
End Sub
End Class
Interesting is that if I have already some new Messages in my Messagestable before I run the programm they are going to be displayed correctly.
If I display the sheets using Form.ShowDialog() it works as well but its not how I want it to work.
As I am out of ideas I hope you can help me.
You are running into issues because the change event of SqlDependency occurs on a different thread that your UI thread. From the SqlDepending documentation:
The OnChange event may be generated on a different thread from the
thread that initiated command execution.
When calling sheet.Show() on a non UI thread, Show() will lockup because there is no message loop to handle the UI events. Use Invoke() on ImsMain to create and show the ImsSheet on your UI thread.