Hi, I'm having a few problems with a project in VB and I was hoping you could help me figure them out.
The first problem I'm having is this:
I'm trying to update stock in a table using SQL through vb.net, the SQL code looks fine and I can't see any problems in it, but it keeps telling me that there was a problem with an incompatible date format - the table being written to is in a sql database and the dates are both set to 'datetime'.
This is what I'm using to write to the table:
I can't figure out what's wrong with it...
The second problem is this:
I'm trying to use a textfile to record some simple stats and then use them to generate a bar graph but I get "Object reference not set to an instance of an object." error...I can't see where the problem is here, it's probably something obvious but this is the code I'm using to write to the file:
I thought it could be something to do with genre, but when I looked at it in debug mode it had the correct value for it, here's where genre is from:
They're both probably some stupid thing I've forgotten to do or check as I'm pretty new to programming, but I'd appreciate some help
The first problem I'm having is this:
I'm trying to update stock in a table using SQL through vb.net, the SQL code looks fine and I can't see any problems in it, but it keeps telling me that there was a problem with an incompatible date format - the table being written to is in a sql database and the dates are both set to 'datetime'.
This is what I'm using to write to the table:
VB.NET:
DataCommand.CommandText = "INSERT INTO [Rented DVDs](MemberID,DVDID,RentedDateRented,RentedDateDue,RentedOverdue) VALUES('" _
& Trim(TextBox2.Text) & "','" & Trim(TextBox1.Text) & "','" & DateTime.Today.Date() & _
"','" & DateTime.Today.Date.AddDays(Trim(TextBox3.Text)) & "','No')"
The second problem is this:
I'm trying to use a textfile to record some simple stats and then use them to generate a bar graph but I get "Object reference not set to an instance of an object." error...I can't see where the problem is here, it's probably something obvious but this is the code I'm using to write to the file:
VB.NET:
Public Class RentADVD
Dim Valid As Boolean = False
Dim MemVal As Boolean = False
Dim DVDVal As Boolean = False
Dim DaysVal As Boolean = False
Dim DVDChecker As String = ""
Dim MemChecker As String = ""
Dim InStock As Integer = 0
Dim Genre As String
Dim Reader As System.IO.StreamReader = System.IO.File.OpenText("Stats.txt")
Dim Writer As System.IO.StreamWriter
Dim StringFind As Integer
Dim SaleString As String
Dim Sales As Integer
Public Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Dim DataConnect As SqlServerCe.SqlCeConnection
Dim DataCommand As SqlServerCe.SqlCeCommand
Dim Line As String = "0"
Do
Line = Reader.ReadLine()
'The line below is where I get the error.
If Line.StartsWith(Genre) Then
StringFind = Line.IndexOf(",")
SaleString = Line.Substring(StringFind)
Sales = CInt(SaleString + 1) + 1
Writer.WriteLine(Genre, Sales)
ElseIf EOF("Stats.txt") = True Then
Writer.WriteLine(Genre, 1)
End If
Loop Until (Line = Nothing)
VB.NET:
Public Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
Dim CheckDVD As SqlServerCe.SqlCeCommand
Dim DataConnect As SqlServerCe.SqlCeConnection
Dim DataR As SqlServerCe.SqlCeDataReader
If TextBox1.Text <> DVDChecker Then
DVDChecker = ""
End If
Try
If TextBox1.TextLength = 4 Then
DataConnect = Connect()
DataConnect.Open()
CheckDVD = DataConnect.CreateCommand
CheckDVD.CommandText = "SELECT * FROM Rental WHERE DVDID=" & Trim(TextBox1.Text)
DataR = CheckDVD.ExecuteReader
While DataR.Read
InStock = DataR(4)
DVDChecker = DataR(0)
Genre = DataR(3)
End While
If DVDChecker = Nothing Then
MessageBox.Show("This DVD ID does not exist in the database!")
ElseIf InStock < 1 Then
MessageBox.Show("This DVD is not in stock!")
End If
DataConnect.Close()
End If
Catch ex As Exception
MessageBox.Show("There was a problem connecting to the database!")
End Try
They're both probably some stupid thing I've forgotten to do or check as I'm pretty new to programming, but I'd appreciate some help