I am very new to VB 2015. I want to learn about database update command. I try to understand SqlDataAdapter. Could anyone please advise me? As my code below, it run completely with no error, but my database table (WORKSHEET) was not updated.
Imports System.Data.SqlClient
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim command2 As String
command2 = "Update WORKSHEET set cancel_flag = 'Y' WHERE CNumber LIKE #reversalNumber"
Using con2 As New SqlConnection(WindowsApplication1.My.Settings.SaleCommDatabaseConnectionString)
Using cmd2 As New SqlCommand(command2)
Using oda2 As New SqlDataAdapter
cmd2.Connection = con2
con2.Open()
cmd2.Parameters.Add("#reversalNumber", SqlDbType.VarChar, 10, "15332")
oda2.UpdateCommand = New SqlCommand(command2, con2)
End Using
End Using
End Using
MsgBox("ggggg")
End Sub
End Class
The SqlDataAdapter class is useful for applying changes from a DataSet to the database. Try filling a DataSet with the modified data, and then apply changes using the adapter's update method (oda2.Update(WORKSHEET)).
EDIT: Make sure that you fill the DataSet with the data by using the SqlDataAdapter's Fill method.
oda2.Fill(yourDataSet)
Before this, you need to select the proper command with oda2.SelectCommand = YourCommand.
Related
So I have been able to connect my database to VB forms, and I am also able to see the table and the fields within. But I can't figure how to make the data appear in the table because it's just blank.
I do have some data stores in the actual access database but it won't show up in my program.
Is there a particular code I need to write? This is what I have so far. The database is called the 'POS system'.
Private Sub OrdersBindingNavigatorSaveItem_Click(sender As Object, e As EventArgs) Handles OrdersBindingNavigatorSaveItem.Click
Me.Validate()
Me.OrdersBindingSource.EndEdit()
Me.TableAdapterManager.UpdateAll(Me.POS_systemDataSet)
End Sub
It is usually a good idea to separate your database code from your user interface code. Create a connection and a command in a Using block so they will be closed and disposed at End Using. Pass the connection string to the constructor of the connection. Pass the CommandText and connection to the constructor of the command. Open the connection and execute the command returning a DataReader to load the DataTable.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim dt = GetData()
DataGridView1.DataSource = dt
End Sub
Private Function GetData() As DataTable
Dim dt As New DataTable
Using cn As New OleDbConnection("Your connection string"),
cmd As New OleDbCommand("Select * From SomeTable;", cn)
cn.Open()
Using reader = cmd.ExecuteReader
dt.Load(reader)
End Using
End Using
Return dt
End Function
I can't figure out why my code won't save to my .accdb database.
I am fetching data from a .accdb database file and displaying it in a DataGridView, and then allowing changes to be made to it there. (This is a stock control system.) After making changes, the user is meant to be able to send the data back so it is saved in the .accdb file.
I have looked online everywhere and tried multiple different ways of doing this. This is the way I am currently using to solve the problem, but when running the code it does not save to the .accdb file. (However, it throws up no errors.)
Public Class Database
Dim datatable As DataTable
Dim adapter As OleDb.OleDbDataAdapter
Dim dbCon As New OleDb.OleDbConnection
Dim dbProvider As String = "PROVIDER=Microsoft.ACE.OLEDB.12.0;"
Dim dbRsrc As String = "Data Source =" & System.IO.Directory.GetCurrentDirectory & "/Resources/List.accdb"
Dim binding As BindingSource
Dim cmdBuilder As OleDb.OleDbCommandBuilder
Private Sub Database_Load(sender As Object, e As EventArgs) Handles MyBase.Load
dbCon.ConnectionString = dbProvider & dbRsrc
dbCon.Open()
adapter = New OleDb.OleDbDataAdapter("Select * FROM List", dbCon)
datatable = New DataTable
adapter.FillSchema(datatable, SchemaType.Source)
adapter.Fill(datatable)
binding = New BindingSource
binding.DataSource = datatable
dbCon.Close()
StockTable.DataSource = binding
End Sub
Private Sub SaveBtn_Click(sender As Object, e As EventArgs) Handles SaveBtn.Click
'insert validation here
Try
dbCon.ConnectionString = dbProvider & dbRsrc
dbCon.Open()
cmdBuilder = New OleDb.OleDbCommandBuilder(adapter)
adapter.AcceptChangesDuringUpdate = True
adapter.Update(datatable)
dbCon.Close()
Catch ex As Exception
MsgBox(ex.Message.ToString() & " Save Unsuccessful.")
End Try
End Sub
End Class
Not sure where I'm going wrong - when I hit the 'save' button, it should connect to the database, build a SQL query to update it and then update my datatable + .accdb database, right?
To test it, I've tried editing multiple columns and saving it, but when opening the file it still says the same values as it had before.
Any suggestions/pointers? I'm pretty newbie to VB.NET, learnt it about 3 months ago and only just starting to get fully into it.
Many thanks to the user "jmcilhinney" who helped me to reach this answer. I feel highly stupid at not realising that my code was working.
I used
Debug.WriteLine("Update value: " & adapter.Update(datatable))
Debug.WriteLine("Connection str: " & dbProvider & dbRsrc)
to find that my update command worked, and that in fact the output of my database file was in the /bin/ folder. I didn't realise that it used the /bin/ folder, and was looking in the root folder with the .VB files, etc.
I have a problem. In the properties of listview which is checkboxes = "True". Using this checkbox, I want to delete the data in listview and in the database.
Below is the code:
If MessageBox.Show("Do you really want to DELETE this record?", "Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Warning) = DialogResult.No Then
MsgBox("Operation cancel", MsgBoxStyle.Information, "Information")
End If
dbSource = "Data Source=LAILATUL-PC\SERVER;Initial Catalog=HotelManagementSystem;Integrated Security=True"
Dim sql As String = "DELETE FROM [Room] WHERE Room_Code = #code"
Using con = New SqlConnection(dbSource)
Using cmd = New SqlCommand(sql, con)
con.Open()
For Each lvItem As ListViewItem In ListViewRoom.Items
If lvItem.Checked Then
cmd.Parameters.AddWithValue("#code", ColumnRoomCode.Text)
cmd.ExecuteNonQuery()
lvItem.Remove()
End If
Next
End Using
End Using
Using above code, only the data in listview is deleted. The data in the database not deleted.
The interface for listviewitem:
Thank you if you all can help me. :)
A Command should be executed to have any effect on the database. You need to add this
cmd.ExecuteNonQuery()
in every loop.
Also the connection could be opened just before entering the loop and should be closed afterward. (Using Statement is recommended here)
Said that, please take a look on Parameterized queries because your code is open to Sql Injections and parsing problems. Also the sql command to delete a record doesn't need a list of fields after the FROM table part.
Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
dbSource = "Data Source=LAILATUL-PC\SERVER;Initial Catalog=HotelManagementSystem;Integrated Security=True"
' Parameterized query
Dim sql As String = "DELETE FROM [Room] WHERE Room_Code = #code"
' Using statement to ensure proper closing and disposing
' of the objects SqlConnection and SqlCommand
using con = New SqlConnection(dbSource)
using cmd = New SqlCommand(sql, con)
con.Open()
' Add a parameter just one time before the loop with an empty string
cmd.Parameters.AddWithValue("#code", "")
For Each lvItem As ListViewItem In ListViewRoom.Items
If lvItem.Checked Then
' Set the parameter value with the value extracted from the ListViewItem
Dim RoomCode = lvItem.Text
cmd.Parameters("#code").Value = RoomCode
cmd.ExecuteNonQuery()
lvItem.Remove()
End If
Next
End Using
End Using
End Sub
One last note. The ColumnRoomCode textbox (?) is always the same, so calling delete one time is enough, but I suppose that this should be changed with some value extrated by you current ListViewItem
I have some textboxes (using VS2010) I'm trying to populate with values from columns in a SQL Server database based on what item someone selects from a combobox. At first I was able to display the values for the first item in the combobox, but now nothing at all displays when I debug. Code:
Private Sub loadfields(sender As System.Object, e As System.EventArgs) Handles client_selection_combobox.SelectedIndexChanged
Using myconnection As New SqlConnection("connection string")
Dim loadfields As String = "SELECT company FROM ClientFileDatabase WHERE ClientFileDatabase.File_Name=#company;"
Dim loadfields_sqlcommand As New SqlCommand(loadfields, myconnection)
loadfields_sqlcommand.Parameters.Add("#company", SqlDbType.NVarChar)
loadfields_sqlcommand.Parameters("#company").Value = client_selection_combobox.SelectedIndex.ToString
Dim loadfields_dataadapter As New SqlDataAdapter
loadfields_dataadapter.SelectCommand = loadfields_sqlcommand
Dim loadfields_dataset As DataSet = New DataSet()
loadfields_dataadapter.Fill(loadfields_dataset, "ClientFileDatabase")
Dim loadfields_dataview = New DataView(loadfields_dataset.Tables("ClientFileDatabase"))
companyname_textbox.DataBindings.Clear()
companyname_textbox.DataBindings.Add("Text", loadfields_dataview, "Company")
taxid_textbox.DataBindings.Clear()
taxid_textbox.DataBindings.Add("Text", loadfields_dataview, "TaxIDNumber")
accountmanager_textbox.DataBindings.Clear()
accountmanager_textbox.DataBindings.Add("Text", loadfields_dataview, "AccountManager")
etc...
End Using
End Sub
I've also tried using the SelectedValueChanged and SelectionChangeCommitted event handlers to no avail. Also tried using a refresh after setting the databindings, didn't help. Any advice welcome, thanks!
I personally like to use datatables, I find them easier to work with. I'm sure you will have more code to check to make sure dt.rows.count > 0 before actually attempting to work with the data, but here is how I would do it.
Dim loadfields_dataadapter As New SqlDataAdapter
Dim dt As New DataTable
loadfields_dataadapter.Fill(dt)
companyname_textbox.text = dt.Rows(0).Item("Company")
taxid_textbox.text = dt.Rows(0).Item("TaxIDNumber")
accountmanager_textbox.text = dt.Rows(0).Item("AccountManager")
Also, keep in mind that NULL fields in the database can cause runtime errors, so you may have to check for those as well.
I am facing a problem displaying the records of my table on the visual basic form I have created.
This is my code :
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
myconnection = New SqlConnection("server=HOME-PC\SQLEXPRESS;uid=sa;pwd=123;database=college")
myconnection.Open()
mycommand = New SqlCommand("SELECT * from demo3)", myconnection)
Dim mySqlDataAdapter As New SqlDataAdapter(mycommand)
Dim mydsStudent As New DataSet()
mySqlDataAdapter.Fill(mydsStudent, "Student")
ra = mycommand.ExecuteNonQuery()
MessageBox.Show("Data Displayed" & ra)
myconnection.Close()
End Sub
End Class
Note: my database name is "college" , table name is "demo3" . Table contains 2 columns namely name and roll no. How to display the data in those columns on the visual basic form that I have created ?
You don't need to call execute non query. You can bind the dataset to a DataGridView. Like this
Dim DataGridView1 as new DataGridView()
DataGridView1.DataSource = mydsStudent
'Your table goes here, not sure about the exact propety name, hope it works.
DataGridView1.DisplayMember = "demo3"
Me.Controls.Add(DataGridView1)