Help my code is not running but its catching my error message, I want to show the images from my database and i will pass it to my picture box
'This is my code
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtsearch.Click
Try
disconnect()
connect()
cmd = New Odbc.OdbcCommand("Select * FROM tblemployee WHERE lname ='" & Trim(TextBox1.Text.TrimEnd()) & "'", con)
dr = cmd.ExecuteReader
If dr.Read() Then
PictureBox1.Image = (dr("emp_pix"))
Else
MessageBox.Show("No Information Record, Please Name!")
End If
Catch ex As Exception
Debug.WriteLine("Please try again" & ex.Message)
End Try
End Sub
You can't display directly byte as Image. you need to convert it and display it.
Try like this
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtsearch.Click
Try
disconnect()
connect()
cmd = New Odbc.OdbcCommand("Select * FROM tblemployee WHERE lname ='" & Trim(TextBox1.Text.TrimEnd()) & "'", con)
dr = cmd.ExecuteReader
If dr.Read() Then
Dim bytBLOBData() As Byte = dr("emp_pix")
Dim stmBLOBData As New MemoryStream(bytBLOBData)
PictureBox1.Image = Image.FromStream(stmBLOBData)
Else
MessageBox.Show("No Information Record, Please Name!")
End If
Catch ex As Exception
Debug.WriteLine("Please try again" & ex.Message)
End Try
End Sub
Related
im trying to create a login form in vb.net with SQLite with this code
Imports System.Data.SQLite
Public Class frmLogin
Private Sub btnlogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnlogin.Click
Dim table As DataTable = Nothing
Dim da As New SQLiteDataAdapter("Select * from user_tbl where username='" & txtuser.Text & "'and pass_id='" & txtpass.Text & "'", myconn)
Try
If txtuser.Text = "" And txtpass.Text = "" Then
MessageBox.Show("Please fill Username and Password", "Important", MessageBoxButtons.OK, MessageBoxIcon.Information)
txtuser.Focus()
Else
da.Fill(table)
If table.Rows.Count > 0 Then
frmMain.Show()
Me.Close()
Else
MessageBox.Show("login not successful")
End If
da.Dispose()
End If
Catch ex As Exception
MessageBox.Show(ex.ToString)
End Try
End Sub
Private Sub frmLogin_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
ConnectME()
End Sub
End Class
but i keep getting an error at line 26 "da.fill(table)"
Here is what the error says:
Here are two lines of your code:
Dim table As DataTable = Nothing
da.Fill(table)
You have no code in between that assigns an object to that table variable. Why exactly are you surprised that there's an issue here? If I told you to fill a bag and then handed you no bag, how exactly would you go about filling it? You couldn't, because you can't fill a bag that doesn't exist, yet you expect your app to be able to fill a DataTable that doesn't exist.
i need help in refresh the datagridview. I create a Update button and show button but it didn't refresh. but i check in my database access it update successful
Imports System.Data
Imports System.Data.OleDb
Public Class Form2
Public con As OleDbConnection
Public da As OleDbDataAdapter
Public ds As New DataSet
Public cmd As OleDbCommand
Public dr As OleDbDataReader
Dim count As Integer = 100
Dim ID As String
Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Try
'Establish connection
con = New OleDbConnection("Provider = Microsoft.ACE.OLEDB.12.0; Data Source = C:\Users\m_j_g\Documents\Visual Studio 2010\Projects\DatabaseApplication\Department.accdb")
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Private Sub btnShow_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnShow.Click
Try
'establish connection
con = New OleDbConnection("provider = Microsoft.ACE.OLEDB.12.0; data source = C:\Users\m_j_g\OneDrive\Documents\Database1.accdb")
'execute sql query
da = New OleDbDataAdapter("Select * from table1", con)
'Fill Dataset
da.Fill(ds, "table1")
'put data from dataset to datagridview
DataGridView1.DataSource = ds.Tables(0)
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Private Sub btnUpdate_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnUpdate.Click
con = New OleDbConnection("provider = Microsoft.ACE.OLEDB.12.0; data source = C:\Users\m_j_g\OneDrive\Documents\Database1.accdb")
Try
con.Open()
cmd = New OleDbCommand("Update table1 set SurName='" & TextBox2.Text & "', FirstName='" & TextBox3.Text & "' where EmailAddress='" & TextBox5.Text & "'", con)
'Execute UPDATE Query
cmd.ExecuteNonQuery()
MsgBox("Record Updated Successfully..." & Chr(13) & "Email Address: " & TextBox5.Text & Chr(13) & "SurName: " & TextBox2.Text & Chr(13) & "FirstName: " & TextBox3.Text)
con.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
I am newbie in programming Thank you for your help
You need to rebind the Grid after performing the update, Follow these steps this may help you:
Define a Method for binding the giridiew, this will populate the grid with values from the DB:
Public Sub bindMyGrid()
con = New OleDbConnection("provider = Microsoft.ACE.OLEDB.12.0; data source = C:\Users\m_j_g\OneDrive\Documents\Database1.accdb")
da = New OleDbDataAdapter("Select * from table1", con)
da.Fill(ds, "table1")
DataGridView1.Rows.Clear() '<-- new line added
DataGridView1.DataSource = ds.Tables(0)
End Sub
Call the method in the click event of the show button to populate the grid:
Private Sub btnShow_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnShow.Click
Try
bindMyGrid()
Catch ex As Exception
' handle error here
End Try
End Sub
Perform the update operation on update button click, and call the method again to get the latest values.
Private Sub btnUpdate_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnUpdate.Click
Try
'Perform the update operations here
' Call bindMyGrid() to rebind the grid
bindMyGrid() 'this will populate the new value to the grid.
Catch ex As Exception
'Handle error here
End Try
End Sub
I use following code to update database record after retrieving data to the text boxes via a datagridview.
But this gives me an exception as object reference not set to an instance of the object. Please help
Private Sub DataGridView_CellClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridViewUserType.CellClick
Dim i As Integer
i = DataGridViewUserType.CurrentRow.Index
If i >= 0 Then
Me.txtBoxID.Text = DataGridViewUserType.Item(0, i).Value
Me.txtBoxUserType.Text = DataGridViewUserType.Item(1, i).Value
Else
MessageBox.Show("Empty Row Clicked")
End If
End Sub
Private Sub btnUserTypeUpdate_Click(sender As Object, e As EventArgs) Handles btnUserTypeUpdate.Click
Try
con.Open()
cmd.Connection = con
cmd.CommandText = "UPDATE dbo.User_Type SET Type = #tp WHERE Type_ID = #ID"
cmd.Parameters.AddWithValue("#ID", txtBoxID.Text)
cmd.Parameters.AddWithValue("#tp", txtBoxUserType.Text)
cmd.ExecuteNonQuery()
MessageBox.Show("Successfully Updated")
Catch ex As Exception
MessageBox.Show("Error while inserting record on table..." & ex.Message, "Update Records")
Finally
con.Close()
btnUserTypeSave.Show()
txtBoxID.Clear()
txtBoxUserType.Clear()
End Try
End Sub
Thankz Fabio
The error was with "cmd"
I just put Dim cmd As SqlCommand = New SqlCommand before using it and now it is functioning.
Thankz All
I'm a beginner in vb.net
I've got the following Error upon executing the Insert-Statement
syntax error in INSERT INTO statement
Here is my code:
Private Sub cmdadd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdadd.Click
Try
Dim sql As String = " INSERT INTO [Login1] ([ID],[Username],[Password])" & _
" VALUES(?,?,?)"
Dim cmd As New OleDbCommand
With cmd
.Connection = con
.CommandText = sql
.Parameters.AddWithValue("?", txtid)
.Parameters.AddWithValue("?", txtuser)
.Parameters.AddWithValue("?", txtpass)
.ExecuteNonQuery()
End With
MsgBox("The Data Has Been Added")
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
Could anyone help me?
Try to use sql parameter names
Private Sub cmdadd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdadd.Click
Try
Dim sql As String = " INSERT INTO [Login1] ([ID],[Username],[Password])" & _
" VALUES(#ID,#Username,#Password)"
Dim cmd As New OleDbCommand
With cmd
.Connection = con
.CommandText = sql
.Parameters.AddWithValue("#ID", txtid)
.Parameters.AddWithValue("#Username", txtuser)
.Parameters.AddWithValue("#Password", txtpass)
.Open()
.ExecuteNonQuery()
.Close()
End With
MsgBox("The Data Has Been Added")
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
Note that: You should properly close your connections after you use them. Therefore following code may be better.
Private Sub InsertLogin()
Dim sql As String = " INSERT INTO [Login1] ([ID],[Username],[Password])" & _
" VALUES(#ID,#Username,#Password)"
Using con As New OleDbConnection(ConnectionStringHERE)
Using cmd As New OleDbCommand
Dim cmd As New OleDbCommand
cmd.Connection = con
cmd.CommandText = sql
cmd.Parameters.AddWithValue("#ID", txtid)
cmd.Parameters.AddWithValue("#Username", txtuser)
cmd.Parameters.AddWithValue("#Password", txtpass)
con.Open()
cmd.ExecuteNonQuery()
con.Close()
End Using
End Using
End Sub
Private Sub cmdadd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdadd.Click
Try
InsertLogin()
MsgBox("The Data Has Been Added")
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
Here, I used cmd. syntax, it is no different then using With.
You have to name the sql parameters.
Look at the examples in the documentation: http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlparametercollection.addwithvalue%28v=vs.110%29.aspx
I have a DataGrid and many text fields to add data into the database. When i add a new data, it gets updated in the database and in the data grid.But when i delete the data, it gets deleted only from the database. It doesn't get updated in the data grid.
When i try to update the data, it updates only one record at a time.when i try for another record it gives me a error "The variable name '#date' has already been declared. Variable names must be unique within a query batch or stored procedure." I have to close and reopen the form to update a new record.
Imports System.Data.SqlClient
Public Class Form
Dim con As New SqlClient.SqlConnection("Server = DEL-PC; Database=Shj; Trusted_Connection=yes;")
Dim cmd As New SqlCommand
Dim dr As SqlDataReader
Dim ds As DataSet
Dim da As SqlDataAdapter
Private Sub Form_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
SqlDataAdapter1.Fill(DataSet11)
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles newbtn.Click
If RegNoTextBox.Text <> "" Then
cmd.Connection = con
con.Open()
cmd.CommandText = "insert into WaterProofing(Date,RegNo) values ('" & DateDateTimePicker.Value & "','" & RegNoTextBox.Text & "')"
cmd.ExecuteNonQuery()
Call showdata()
con.Close()
Else
MessageBox.Show("Please enter registration number")
End If
End Sub
//updation
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles editbtn.Click
cmd.Parameters.AddWithValue("#date", DateDateTimePicker.Value)
cmd.Parameters.AddWithValue("#regno", RegNoTextBox.Text)
cmd.Connection = con
con.Open()
cmd.CommandText = "update WaterProofing set RegNo= #regno where date=#date"
cmd.ExecuteNonQuery()
Call showdata()
con.Close()
MessageBox.Show("Details Updated!")
End Sub
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles deletebtn.Click
cmd.Connection = con
con.Open()
cmd.CommandText = "delete from WaterProofing where date='" & DateDateTimePicker.Value & "'"
cmd.ExecuteNonQuery()
Call showdata()
con.Close()
MessageBox.Show("Details Deleted!")
End Sub
Sub showdata()
SqlDataAdapter1.Fill(DataSet11, "WaterProofing")
With DataGridView
.Update()
End With
End Sub
End Class
Please help me in deletion and updating.
You're adding parameters before declaring CommandText at Button2_Click
Try it in this way:
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles editbtn.Click
Try
Dim command As New SqlCommand
con.Open()
command.Connection = con
command.CommandText = "update WaterProofing set RegNo= #regno where date=#date"
command.Parameters.AddWithValue("#date", DateDateTimePicker.Value)
command.Parameters.AddWithValue("#regno", RegNoTextBox.Text)
command.ExecuteNonQuery()
con.Close()
Call showdata()
MessageBox.Show("Details Updated!")
Catch ex as Exception
MessageBox.Show(ex.Message)
End try
End Sub
UPDATE
Basically you have to do the same thing when you load the DataGridView for the first time in order to refresh the DataGridView with the current data from database after deleting or updating records, so your ShowData Sub might look something like this
Private Sub ShowData()
Dim Connection As SqlConnection
Connection = New SqlConnection("YourConnectionString")
Try
Connection.Open()
Dim SQL As String = "SELECT Field1, Field2, Field3 FROM Table"
Dim DS As New DataSet
Dim Adapter As New SqlDataAdapter(SQL, Connection)
Adapter.Fill(DS)
DataGridView.DataSource = DS.Tables(0)
DataGridView.Refresh()
Catch ex As Exception
MessageBox(ex.Message)
Finally
Connection.Close()
End Try
End Sub
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles deletebtn.Click
Try
Dim command As New SqlCommand
con.Open()
command.Connection = con
command.CommandText = "delete from WaterProofing where date='" & DateDateTimePicker.Value & "'"
command.ExecuteNonQuery()
con.Close()
Call ShowData_Delete()
MessageBox.Show("Details Deleted!")
Catch ex As Exception
MessageBox.Show(ex.Message)
Finally
End Try
End Sub
Private Sub ShowData_Delete()
Dim Connection As SqlConnection
Try
Connection = New SqlConnection("Server = DEL-PC; Database=Shj; Trusted_Connection=yes;")
Connection.Open()
Dim SQL As String = "SELECT * from WaterProofing"
Dim DS As New DataSet
Dim Adapter As New SqlDataAdapter(SQL, Connection)
Adapter.Fill(DS)
DataGridView1.DataSource = DS.Tables(0)
DataGridView1.Refresh()
Catch ex As Exception
MessageBox.Show(ex.Message)
Finally
Connection.Close()
End Try
End Sub