Error on data mismatch doesn't stop - vb.net

I can keep getting 'data type mismatch on citerio expression'
Because TimeOfOrder is a data/time in the access, i tried converting it to a string. It didnt work as well.
So then i tried removing that field to find the source of the problem the same error still appears.
This is my code so far:
Private Sub Lists_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Lists.SelectedIndexChanged
Dim Sql As String
Dim data As dbase.OleDbDataReader
Dim cmd As dbase.OleDbCommand
conn.Open() ' start the connection
Sql = "select * from corder where OrderID = """ & Lists.Text & """"
cmd = New dbase.OleDbCommand(Sql, conn) ' how the commad is run on this connection
data = cmd.ExecuteReader
data.Read()
TextBox1.Text = data("TableNumber")
TextBox2.Text = data("Status")
TextBox3.Text = data("TimeOfOrder".ToString("f"))
textbox4.text = data("Orders")
conn.Close()
End Sub

You can modify like this. OrderID is read as text from Lists.Text so it is "ready" to be concatenated with the SQL string as is:
Private Sub Lists_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Lists.SelectedIndexChanged
Dim Sql As String
Dim data As dbase.OleDbDataReader
Dim cmd As dbase.OleDbCommand
conn.Open() ' start the connection
Sql = "select * from corder where OrderID = " & Lists.Text & ""
cmd = New dbase.OleDbCommand(Sql, conn) ' how the commad is run on this connection
data = cmd.ExecuteReader
data.Read()
TextBox1.Text = data("TableNumber")
TextBox2.Text = data("Status")
' Cast/format the field value, not the field name.
TextBox3.Text = data("TimeOfOrder").ToString("f")
textbox4.text = data("Orders")
conn.Close()
End Sub

Related

How to read and move read content via SQL into variables within VB.net and use a connectionstring from a module in forms?

This is my first question, by the way - and I'm not sure exactly how to ask, or say what's wrong. There's 3 things I can't sort so any help would be appreciated.
Module:
This and the first (login) form work as they are but I couldn't get either Form to reference con.connectionstring for them to use without having to re-use the string contained in "" (as they do below) - my attempts ended up with errors including saying that the state couldn't be changed as the connection was already open, but I'd like the same one string to be referenced from the Forms.
Module ConnectionModule
Public con As OleDb.OleDbConnection = New OleDb.OleDbConnection
Public da As OleDb.OleDbDataAdapter
Public ds As DataSet = New DataSet
Public Path As String = Application.StartupPath
Public Sub OpenDb()
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=F:\Computing A2\CG4 Coursework\Greener Cleaning\dbCoursework.accdb"
con.Open()
If con.State = ConnectionState.Closed Then
MsgBox("Connection to db not made.")
End If
End Sub
Public CurrentUser As String = Nothing
End Module
The First Form:
Public Class LoginForm
Private Sub LoginForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
OpenDb()
con.Close()
End Sub
Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
Dim ID As String = txtID.Text
Dim Pass As String = txtPassword.Text
If IsNumeric(ID) = False Or ID.Length > 4 Or Pass = Nothing Then
MsgBox("Staff ID is a 4-digit number and Password must not be blank.")
Else
Dim con As New System.Data.OleDb.OleDbConnection()
OpenDb()
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=F:\Computing A2\CG4 Coursework\Greener Cleaning\dbCoursework.accdb"
Try
Dim sql As String = "SELECT * FROM tblStaff WHERE [StaffID]='" & ID & "' AND [Pword] = '" & Pass & "'"
Dim sqlCom As New System.Data.OleDb.OleDbCommand(sql)
'Open Database Connection
sqlCom.Connection = con
con.Open()
Dim sqlRead As System.Data.OleDb.OleDbDataReader = sqlCom.ExecuteReader()
If sqlRead.Read() Then 'Correct:
MenuForm.Show()
Me.Hide()
CurrentUser = ID
Else 'Incorrect:
MsgBox("Staff ID or Password incorrect.")
txtPassword.Text = ""
txtID.Text = ""
txtID.Focus()
End If
Catch ex As Exception
MsgBox("Database Connection Error.")
End Try
con.Close()
End If
End Sub
End Class
A form to change the password:
The problem here is that lblUser (A clarification for the user to tell them which password will be changed) only outputs the data already within the program as a variable: CurrentUser (as assigned upon successful login). No error is produced but the full name of the user isn't shown (or possibly read from the database).
I'm also unsure how the UPDATE SQL command should be contained within the second procedure, btnAccept_click, here. What the syntax is, basically. I haven't found a clear example to look at.
Imports System.Data.OleDb
Public Class PasswordForm
Private Sub PasswordForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
con = New System.Data.OleDb.OleDbConnection()
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=F:\Computing A2\CG4 Coursework\Greener Cleaning\dbCoursework.accdb"
Dim Returned(2) As String
CurrentUser = CurrentUser
Dim cmd As OleDbCommand = New OleDbCommand("SELECT [Title], [Forename], [Surname] FROM tblStaff WHERE [StaffID]='" & CurrentUser & "'", con)
Try
con.Open()
Dim reader As OleDbDataReader = cmd.ExecuteReader()
If reader.HasRows Then
reader.Read()
'Makes db contents variables
Returned(0) = reader.Item("[Title]").ToString
Returned(1) = reader.Item("[Forename]").ToString
Returned(2) = reader.Item("[Surname]").ToString
End If
reader.Close()
Catch ex As Exception
Me.Hide()
MsgBox("Database Connection Error.")
Finally
con.Close()
End Try
lblUser.Text = "Current User: " & CurrentUser & Returned(0) & Returned(1) & Returned(2)
''Only outputs CurrentUser
End Sub
Private Sub btnAccept_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAccept.Click
Dim Current As String = txtCurrent.text
Dim NewPass As String = txtNew.Text
'Verification
If txtNew.Text = txtConfirm.Text And NewPass.Length <= 20 Then
Dim cmd As OleDbCommand = New OleDbCommand("UPDATE tblStaff SET [Pword]='" & NewPass & "' WHERE [StaffID]='" & CurrentUser & "'", con)
End If
End Sub
End Class
Thank you, again, for anyone with ideas (especially exact code).
Oh and throughout what's here there are no errors thrown. Just missing content.
you are opening the connection in openDB() and you are trying to open it again in form1, this will throw the error you are getting. So comment all the con related lines in your form. Same comment for your passowrd form also.
'Dim con As New System.Data.OleDb.OleDbConnection()
OpenDb()
'con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=F:\Computing A2\CG4 Coursework\Greener Cleaning\dbCoursework.accdb"
Try
Dim sql As String = "SELECT * FROM tblStaff WHERE [StaffID]='" & ID & "' AND [Pword] = '" & Pass & "'"
Dim sqlCom As New System.Data.OleDb.OleDbCommand(sql)
'Open Database Connection
sqlCom.Connection = con
'con.Open()
...
end try

How to get count of records in a table?

Someone help me
I am working on our project and I need to check if my DB has already 20 records.
If so, then it will not accept records anymore.
I've been trying the codes below:
Public Class Form1
Dim con As New OleDb.OleDbConnection
Dim ds, ds2 As New DataSet
Dim da, da2 As OleDb.OleDbDataAdapter
Dim sql, sql1 As String
Dim int As Integer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
con.ConnectionString = "Provider=Microsoft.jet.OLEDB.4.0; data source = |datadirectory|\Database6.mdb"
con.Open()
Dim cmd As OleDb.OleDbCommand = New OleDb.OleDbCommand("SELECT * FROM Accounts WHERE Username='" & TextBox1.Text & "'", con)
Dim sdr As OleDb.OleDbDataReader = cmd.ExecuteReader
Dim cmd1 As OleDb.OleDbCommand = New OleDb.OleDbCommand("SELECT * FROM Accounts")
sql = "INSERT INTO Accounts ([Username], [Password], [FirstName], [LastName]) VALUES ('" & TextBox1.Text & "','" & TextBox2.Text & "', '" & TextBox3.Text & "','" & TextBox4.Text & "') "
sql1 = "SELECT Count([AccountID]) FROM Accounts"
cmd = New OleDb.OleDbCommand(sql, con)
cmd1 = New OleDb.OleDbCommand(sql1, con)
Convert.ToInt32(sql1)
cmd1.ExecuteScalar()
If sql1 < 20 Then
MsgBox("Cannot accept records")
ElseIf sdr.HasRows = False Then
cmd.ExecuteNonQuery()
MsgBox("Account Added")
ElseIf sdr.HasRows = True Then
MsgBox("Username is taken")
End If
con.Close()
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Me.Hide()
Form2.Show()
End Sub
End Class
But the convert code fires an error :
Input string was in incorrect format
But if I delete the convert code it gives me the error
Conversion from string "SELECT Count([AccountID]) FROM A" to type 'Double' is not valid."
Help me please.
TIA
I dont know VB all that well, this is from the top of my head. Your trying to convert your SQL text, which will never work. Try something like this:
dim result as object
result = cmd1.ExecuteScalar()
dim count as int
count = Convert.ToInt32(result)
If count < 20 Then

Syntax error in UPDATE statement access database in vb.net

I have just started learning VB.net for several weeks. i want to make a form and send data from a text box to a specific cell in ms access database (*.accdb) file. but the code i have writen gives the following error:
Syntax error in UPDATE statement.
i have checked several books and spent hours on internet, but no answer!
Dim con As New OleDb.OleDbConnection
Dim ds As New DataSet
Dim da As OleDb.OleDbDataAdapter
Dim sql As String
Dim cnn1 As New OleDb.OleDbConnection
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=
E:\Ebook\hararat\GUI\Heat Exchanger Designer\heat.accdb"
con.Open()
sql = "SELECT * FROM flow1"
da = New OleDbDataAdapter(sql, con)
da.Fill(ds, "flow1")
Dim cb As New OleDb.OleDbCommandBuilder(da)
ds.Tables("flow1").Rows(1).Item(1) = "name"
da.Update(ds, "flow1")
con.Close()
You need to use the .QuotePrefix and .QuoteSuffix properties of the OleDbCommandBuilder to wrap table and field names in square brackets. That is, instead of just
Dim cb As New OleDb.OleDbCommandBuilder(da)
you need to do
Dim cb As New OleDb.OleDbCommandBuilder(da)
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
That will generate an UPDATE statement of the form
UPDATE [TableName] SET [ColumnName]= ...
which is necessary if the table name or any of the field names happen to be reserved words in Access SQL.
Try this one
dim sqlupdate as string = "UPDATE tablename SET column_name = '" & textname.text & "' WHERE column_name = '" & textname.text & "'"
Sometimes errors occur when using the following column names: Username, Password, Date, Time, and much more of this type, try to avoid these column names because this might cause the problem of your issue regarding updating tables. Enable for you to update this kind of column name you need to enclose it with [ and ] so it comes like this: [Username], [Date], etc. so the syntax might go like this:
UPDATE tablename SET [Username] = '" & textname.text & "' WHERE column_name = '" & textname.text & "'"
my codes goes like this:
Open_Con()
Dim sqlUpdate As String
Dim sqlUpdatePass As DialogResult
sqlUpdate = "UPDATE tblAccounts SET [Password] = '" & txtRPassword.Text & "' WHERE [Username] = '" & txtUsername.Text & "'"
sqlCmd = New OleDbCommand(sqlUpdate, sqlCon)
Try
sqlUpdatePass = MessageBox.Show("Are you sure to save this changes?", "Save changes?", MessageBoxButtons.YesNo, MessageBoxIcon.Question)
If sqlUpdatePass = vbYes Then
sqlCmd.ExecuteNonQuery()
MsgBox("Changes are now saved", MsgBoxStyle.Information, "New password has been set.")
Call ClearAll()
Me.Hide()
Else
Exit Sub
End If
Catch ex As Exception
MsgBox("Could not perform this task because " & ex.Message, MsgBoxStyle.Exclamation, "Error")
End Try
sqlCmd = Nothing
sqlCon.Close()
hope this things mention above codes helps your problem. have a nice day and happy coding :)
dim sqlupdate as string="UPDATE [tablename] SET [column_name] = '"& textname.text &"' WHERE [column_name] = '"& textname.text &"';"
By enclose attributes with square brackets, it appears to work I have tried it, it works
Imports System.Data.OleDb
Imports System.Data
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'Database2DataSet.identitas' table. You can move, or remove it, as needed.
Me.IdentitasTableAdapter.Fill(Me.Database2DataSet.identitas)
End Sub
Public Sub clean()
TextBox1.Clear()
TextBox2.Clear()
TextBox3.Clear()
TextBox4.Clear()
End Sub
Public Sub read()
Call openconn()
str = "select * from identitas"
dtadapter = New OleDbDataAdapter(str, con)
Dim dg As New DataTable
dg.Clear()
dtadapter.Fill(dg)
dgv.DataSource = dg
End Sub
Public Sub create()
Call openconn()
str = "insert into identitas values ('" & TextBox1.Text & "','" & TextBox2.Text & "','" & TextBox3.Text & "','" & TextBox4.Text & "') "
cmd = New OleDbCommand(str, con)
cmd.Connection = con
cmd.ExecuteNonQuery()
MsgBox("data lebet")
read()
clean()
End Sub
Public Sub update()
Call openconn()
str = "UPDATE identitas SET [Nama] = '" & TextBox2.Text & "',[Alamat] = '" & TextBox3.Text & "', [No] = '" & TextBox4.Text & "' where [NIK] = '" & TextBox1.Text & "'"
cmd = New OleDbCommand(str, con)
cmd.Connection = con
cmd.ExecuteNonQuery()
MsgBox("data ter ubah")
clean()
read()
End Sub
Public Sub delete()
Call openconn()
str = "delete from identitas where NIK = '" & TextBox1.Text & "'"
cmd = New OleDbCommand(str, con)
cmd.Connection = con
cmd.ExecuteNonQuery()
clean()
End Sub
Private Sub btnclose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnclose.Click
Me.Close()
End Sub
Private Sub btnc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnc.Click
create()
End Sub
Private Sub btnr_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnr.Click
read()
End Sub
Private Sub btnclean_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnclean.Click
clean()
End Sub
Private Sub btnd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnd.Click
Dim pesan As String = MsgBox("yakin mau hapus = " & TextBox1.Text & "?", MsgBoxStyle.YesNo)
If pesan = vbYes Then
delete()
End If
read()
End Sub
Private Sub btnu_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnu.Click
update()
End Sub
End Class
I had same problem, this helped.
"Sometimes errors occur when using the following column names: Username, Password, Date, Time, and much more of this type, try to avoid these column names because this might cause the problem of your issue regarding updating tables. Enable for you to update this kind of column name you need to enclose it with [ and ] so it comes like this: [Username], [Date], etc. so the syntax might go like this: "
I renamed the columns in Access (e.g Password1,Username1) as the same words password, username might be reserved in vb.net. Thanks for this response.

Datatable:xml query for xml column

If i load xml datatype column to a datatable then can i perform xml query on it? SQL server supports queries like .exist, .value on xml columns. I am trying those kind of queries on datatable.
Below is a part of code which shows where i am getting error.
Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
Dim timDiff As Double
Dim iter1 As Integer
TextBox1.Text &= Button15.Text & vbNewLine & " Iterations: " & TextBox2.Text & vbNewLine
timDiff = DateAndTime.Timer
Dim SqlAdapter As New SqlDataAdapter
Dim strTemp As String
Dim iRow As Integer
Dim rConn As New SqlConnection("data source=pc91\sqlexpress;user id=admin;password=abc;initial catalog=Checklists;connect timeout=2000;")
rConn.Open()
SqlAdapter = New SqlDataAdapter
sDataSet = New DataSet
sqldatatable = Nothing
SqlAdapter.SelectCommand = New SqlCommand("select * from DesignChanges", rConn)
SqlAdapter.Fill(sDataSet, "tmpTable")
sqldatatable = sDataSet.Tables("tmpTable")
For iter1 = 1 To Val(TextBox2.Text)
Try
For iRow = 0 To sqldatatable.Rows.Count - 1
strTemp = sqldatatable.Rows(iRow).Item("AllotedTo").ToString
Next iRow
Catch ex As Exception
MsgBox(ex.ToString & Space(10) & Err.Description)
End Try
Next
rConn.Close()
SqlAdapter.Dispose()
rConn.Dispose()
sDataSet = Nothing
SqlAdapter = Nothing
rConn = Nothing
timDiff = DateAndTime.Timer - timDiff
TextBox1.Text &= " Total Time Taken: " & timDiff & vbNewLine
End Sub
Private Sub Button17_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button17.Click
bs.DataSource = sqldatatable
DataGridView1.DataSource = bs
End Sub
Private Sub Button18_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button18.Click
bs.Filter = "[UserApproval].exist ('/Root/Row[User=''xyz'']') =1"
End Sub
End Class
In the above code error comes like "The expression contains undefined function call UserApproval.exist()." for the line bs.Filter = "[UserApproval].exist ('/Root/Row[User=''xyz'']') =1" .
If i use .value function then error will come as "The expression contains undefined function call UserApproval.value()."
But the same functions works in SQL query for sql server.
Yes, you can. Did you read this? What kind of queries do not work well?

Visual Basic HowTo: Retrieve Data from .mdf

What am I doing wrong? I have been going at this for a while now... I surrender.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Using sqlCon = New SqlConnection("Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\gadgetDatabase.mdf;Integrated Security=True")
Dim Id As Integer = 2
'With the use of ID, it will get the appName or Application Display Name
sqlCon.Open()
Dim sqlText = "SELECT appName " & _
"FROM appTable " & _
"WHERE Id = #sqlID"
Dim sqlCmd = New SqlCommand(sqlText, sqlCon)
sqlCmd.Parameters.AddWithValue("#sqlID", Id)
'sqlCmd.ToString()
sqlCmd.ExecuteScalar() 'I had these in there before I copied the code over
sqlCon.Close()
Label3.Text = sqlText 'For testing or confirmation it went correctly...
End Using
End Sub
You forgot to call
string apName = sqlCmd.ExecuteScaler();
and retrieve the result.
If a resultset (multiple results) is expected, then call reader = cmd.ExecuteReader() and loop through the results.