I'm using visual basic to code a program to help with weights and center of balance on aircrafts, as I'm my unit's new air load planner. The math isn't hard to do, it's just that much of it is trial and error, and redoing all the arithmetic over and over again until the aircraft's C/B is in acceptable limits can eat some time up. So, since i'm trying to learn programming I thought this might be a good way to use it for a real-world scenario.
I am building a data based application using VB 2008 an SQL Express. I need to create textboxes on my form using code, (With & End With) method. I need a simple code string that will allow the app to check if the field to wich the textbox wil be databound is Nul, If so the textbox will not be created.
At run time my application gives an error of "Conversion from type "DBNull" to type "String" is not valid. In my form only one field - Add_info is an optional field which might be filled or not by the user. Before, I had an error when an apostrophe was used so i updated the code as highlighted below. This in return removed the apostrophe error but generated an error whenever there is an empty additional field.
For irow = 0 To QryColSentDataGridView.Rows.Count - 1 If QryColSentDataGridView.Rows(irow).Cells(3).Value = True Then Try query = "UPDATE gprdsql.TblCollections SET system_time = '" & _ Labeldate.Text & "' where prac_no ='" & _ [Code] .....
I try to compile a project with msbuild.exe I have this error :
vbc : error BC30136: Error creating Win32 resources: Error reading icon '"Recycle Bin Empty.ico"' -- The filename, directory name, or volume label syntax is incorrect.
This icon is the Application icon which is in the same directory of the project.vbc is started with /win32icon:"Recycle Bin Empty.ico" parameter.Don't know why MSBuild can't reach the file.
i have a form with 4 text boxes on them when the user selects add the information from the textboxes saves to my database im just wondering does anyone know how i would make an error message appear if one of the textboxes was blank and stop the new data being saved until all textboxes have data in them?i did write the following peice of code but it did not work Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
When im using a loop in my program and i'm trying to use an Error Provider to pop up whenever a textbox in my groupbox is empty for some reason I cannot get it to work, can anyone tell me what i'm doing wrong?
For Each ctrl As Control In GroupBox1.Controls
If TypeOf ctrl Is TextBox Then If CType(ctrl, TextBox).Text = "" Then
[CODE].............
I'm not receiving any type of error, it's just that when a textbox is blank the error provider is not doing anything.
How to know if the input box did not put anything . I must still put zero in the inputbox so I cannot make a condition that only 1 - 10 is allowed. I need the zero value so how can I identify if that inputbox gives empty result so that I can prompt a msgbox saying you did not put anything?
I'm trying to create a linked list of an array of integers. Why is the following implicit conversion required?
When I run the code that contains that conversion, I get the following error.
As a real-time data acquisition user control data (a packet of an array of bytes) arrives every second, is converted into an integer array and inserted into a linked list.
The most recently arrived data is painted as coordinates on a grid at the right of a PictureBox using Graphics.DrawLine (pen,X1,Y1,X2,Y2).
The oldest data (arriving 120 seconds ago) will be drawn at the leftmost portion of the Picturebox.
Why a linked list rather than a list? To display 120 views of time sequence data, the draw routine the most recently inserted node to a node that points to Nothing. How do I limit the length of the linked list to 120 nodes and always ensure that the last node points to Nothing?
Do While Not item Is Nothing item = item.NextItem Loop
I have an array set up to receive the names of forms when they open. The form name is sent as a Form not a String therefore when I run my code I cannot check for whether the field is empty in the normal way (ie. array(1) = "") as the "" are only usable with strings!
Dim Forms(24) As Form Dim i As Integer Dim Free As Integer = -1
[CODE]...
I only need a solution to do the same as array(1)="" but for windows forms.
I have a form and stored procedure that inserts the data from the form. It works fine except that if a field isn't filled in it doesn't insert a NULL into SQL it inserts "".
I've tried a few different ways but none seem to insert NULL, the one below still inserts "", can anyone point me in the right direction?
Here is the required part of the code, if you require more just let me know.
Dim rdr As SqlDataReader Dim cmdInsert As SqlCommand = New SqlCommand() cmdInsert.CommandText = "spPersonalDetailsInsert"
[Code].....
So if I enter nothing into address1 field it should write NULL to screen but it always writes NOT NULL. What does an empty form field equal? in classic ASP it was always "".
I have a couple of textfields in a Windows form. One of these textfields is allowed to be NULL. When I enter a value for every field, it is all inserted, no problem. When I leave the field (txtGewicht) blank, I can't seem to be able to insert NULL in Access Database.
If Double.TryParse(txtGewicht.Text, 0) Then klant.Gewicht = Double.Parse(txtGewicht.Text) Else
[Code]....
This is what I get:
"Cannot set column 'Gewicht' to NULL, please use DBNull instead"
So I changed 'Nothing' to DBNull.value, but it then tells me that System.DBNull cannot be converted to type Double.
Here's a sub routine that fills a data set with a table which I queried using an Inner Join statement. This output table, has all the required fields and the query works fine. However I want it like so: If a student doesn't have a StudentPrediction.PredictedGrade Field to JOIN and it IS Empty.. Then I still would like it to display the students information just leaving the StudentPrediction.Predicted field empty.
You see I am using a ListView to display the data from when I fill the ListView, but it will only display for people who have a Predicted Grade naturally. So what steps would I need to take to ensure it displays all the information in the Student's table AND for the students who do have predictions that would also be displayed. If the student has no data on PredictedGrades then that column would be blank but the rest of the information still displayed.
Private Sub FillDataset() Dim ConString As String = ("Data Source=USERSQLEXPRESS;Initial Catalog=StudentTeacherDB;Integrated Security=True") Dim QueryString As String = "SELECT Student.FirstName, Student.Surname, Student.Email, [Code] .....
The project I'm working on is a Multichoice RadioButton quiz with answers and percentintegers. At the end there is a MsgBox that gives the number of answers counted 'correct'and the percent 'correct'. Also after you press the confirm button on that MsgBox it emails the results to the built in information given on the SMTP information. What I am trying to do now is show the input typed into the textbox on FormA in the MsgBox at the very end.
I'm using the following to populate a listbox from a sql server:[code]Is Available returns true (It's a bit in sql) or false - Is it possible to replace this with something shorter, say a checkbox or tick image?Also, is it possible to only display actual data rather than the whole field including empty characters? I have a few nchar(30) fields, the above seems to include all 30 character spaces.
I want to generate checkbox field using GridView and system will calculate how many field to display according to number of totalDay. If totalDay stored in database is 7, so upon calling the eventID it will generate 7 checkboxes, D1-D7 checkboxes field will appear; if totalDay is 5, it will generate 5 checkboxes, D1-D5 checkboxes field will appear.
In PHP, I manage to auto generate number of D field I want according to value totalDay. But I do not know how to code in VB. The PC Fair Event has duration 7 days, so it will display 7 checkboxes after user select event and booth to book: The Carnival 2012 has duration 5 days, so it will display 5 checkboxes after user select event and booth to book:
The code in PHP which can generate the checkbox: $query = "select * from booths, eventinfo where booths.eventID=eventinfo.eventID && booths.eventID = ".$id.""; $_SESSION['EVENT_ID']=$id; $result = mysql_query($query); $result2= mysql_query($query); [Code] .....
I am using save file dialogue box and i am saving the contents of richtextbox which is in the form. So i used the coding below. It only creating the empty file but not the text which i typed in the richtextbox.
Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
I have a table with a Real datatype field. I just can't multiply it with other integer fields although the editor doesn't show any error - the result is always '1'.
I am simply trying to get the hexadecimal value of an integer (below 255) and then place this value into a byte. I have been using the hex command, but it converts the value to a string hex value. Its been driving me mad for days now as I just cant seem to sort it!
The code is as follows: tempIntToCompare = CInt(tempValue) tempIntToCompare = tempIntToCompare - LowTemp
I am using VBNET2008 to develop Window Application. I was requested by Business Analyst to create a MultiDimensional Array containing CustID(Integer) and CustomerName(string). I do not know how to declare the MultiDimensional Array VARIABLE as Integer and string.
I have a project that reference from leadtools 16.5, and after that, i want to run my project..i see am error like it " An error occurred creating the form. See Exception.InnerException for details. The error is: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. im using vb 2008 pro
I created a button in my form which is used to add a new textbox.But before that, the button should identify if all the textboxes that have been created are empty.If there is an empty one, it would not add a new one.[code]
I have been tasked to build a simple application that has an input textfield, a button, and a large multiline textfield setup for displaying output> the user enters in the number of rows in the input textfield and presses the button> a pyramid made out of "O" should be created in the output textfield> for example: user enters 3 and presses the button> output in output textfield: O OO OOO OO O Here is the code I came up with so far: Private Sub btndisplay_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btndisplay.Click Dim n As Long Dim lngNum As Integer = CInt(txtinput.Text) For n = 1 To lngNum txtoutput.Text = "0" & vbCrLf Next End Sub
