I have a database with lots of fields, some of which are still empty and are to be filled in at a later stage. Is there any way of writing an IF statement (or any other method) that will allow these empty records to be 'shown' in my textboxes in Visual Studio, without receiving the error:
Conversion from type 'DBNull' to type 'String' is not valid.
How to avoid getting empty fields in a databound combo box?
View 2 RepliesHow to avoid getting empty fileds in a data boud combo box?
View 1 RepliesI'm trying to create a table in Word using data from a table in Access. There are four fields in the access table that I need. 3 fields are text which I can populate the Word without any issues. However the fourth field is a memo with >255 characters.I'm struggling to come up with the proper code to allow me to populate the Word field with the memo data that has more than 255 characters. The code I have so far is listed below. But when it hits the memo field, it crashes on the line I marked with **. I know it's not text, but I've tried many different field types, but nothing has worked so far.[code]...
View 1 RepliesI used to run into problems with this in VB6, too...
If Not ds_Students.Tables(0).Rows(0).Item("ClassDay2").IsNullOrEmpty Then
txtClassDay2.Text = ds_Students.Tables(0).Rows(0).Item("ClassDay2")
End If
This produces "Public member 'IsNullOrEmpty' on type 'DBNull' not found."
And is there a different test for fields of different data types?
I'm trying to add a service company from a vb form to an SQL table. It works as long as I enter something in every field on the form. If not I get a syntax error so I thought I should check that the field values were not null
I've tried to add a sub to check for blanks but it's not working
btw the table will allow nulls for all fields
Private Sub btnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
Try
[Code].....
I am building a vb.net application for a client, and there is a problem. I am connecting to a mySQL server, and using the UPDATE command to update certain fields to the specified values, however, once I run this code, the fields on the mySQL server turn EMPTY. Here is my code :
Sub updateresidents()
'MAKES NO SENSE; UPDATES EMPTY FIELDS ON mySQL SIDE??!!!!!!!!!!!!!!!!!!
Dim connection As MySqlConnection
[Code]....
How to tell the program that if the field is empty to skip it and go to the next step. I have tried IsEmpty (but it tells me the variable IsEmpty was not declared), I have tried to use different If statements but in most cases I get the message
"Conversion from type 'DBNull' to type 'String' is not valid."
I tried using an integer variable and setting it to
'Test = CStr(dt.Rows(I)("socSecNumber")).Length'.
It works for the first step (which makes sense b/c socSecNumber is never empty), but when I set the 2nd and 3rd ones
(TestFName = CStr(dt.Rows(I)("firstName")).Length TestLName = CStr(dt.Rows(I)("lastName")).Length If TestFName > 0 And TestLName > 0 Then...)
Then I am back to getting the message
'Conversion from type 'DBNull' to type 'String' is not valid'.
I do not know anything about recordset and when I did try to use it it displayed the message something like 'get and set are no longer allowed'.
The entire function is below:
Private Sub BtnCreateLetter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCreateLetter.Click
Dim SSN As String = TxtBxSSN.Text
Dim dt As New DataTable()
[Code] .....
Is it possible to include something in the SELECT from table? Such as:
"SELECT * FROM" & Students & "WHERE" * NOT DBNull
or
I do not know if it is possible to use variables in the SELECT from table code but if it is I thought perhaps could make a variable named FieldContents and pass it to a function that would do something like:
"SELECT * FROM" & Students & "WHERE" * FieldContents LIKE '[A-Z]'
why this code returns the property names as column headers and empty fields?
Dim table As New List(Of SalesPersonClass.SalesPersonClass)
Dim i As Integer
For i = 0 To salesPeople.GetUpperBound(0)
table.Add(salesPeople(i))
Next
dgSalesPeople.DataSource = table
i need to display some text boxes, and have the ability for the user to "add another row"
i tried a datalist and a repeater, but it does not show anything at all, when the controls are blank.
<asp:DataList id="dlIso" runat="server" RepeatColumns="2" RepeatDirection="vertical" >
<ItemTemplate>
[Code]....
so in this case "test" does now show at all..
what is the best way to get this accomplished?
I am not able to get an empty point to break the line and be skipped in MSchart. I am using a spline chart for the data and when it reaches an empty point I want to line to break. I have tried setting the marker-style and border-width to nothing and 0 and also tried setting them in code but no success.
View 1 RepliesI'd like to jump in and write a simple application to display fields related to my compact disk library (Disk#, Composer, Work, etc.) in a scrollable window. The current catalog in in a DOS/xBase format, but I can export it to Excel or Access. I am using VB within Visual Studio 2008. Any most effective VB command(s) to use? Is the indicated command used within a looping structure?
View 3 RepliesI have a three-tier Windows Forms DB application in VB.NET. I'm using VS 2005. I'd like to display records in a table in a DataGridView. I can already display the records as is by binding the DataSource to the business class that talks to the DB class:
Dim assetList as List(Of Asset)
assetList = DB_Asset.GetAssetListOrderByID_Asset
AssetDataGridView.DataSource = assetList
"Asset" is my business class, and "DB_Asset" is my DB class that queries the DB to return assetList. Now, Asset has members something like this:
Private m_ID_Asset As Integer
Private m_CategoryID As Integer
Private m_CustodianID As Integer
Private m_ManufacturerID As Integer
Private m_SignedOutToID As Integer
Private m_DefaultLocationID As Integer
Private m_CurrentLocationID As Integer
Private m_DateAcquired As Date
Private m_DateEntered As Date
Private m_EnteredByID As Integer
m _ ID _ Asset contains the primary key for the Asset table in the DB, and everything else of the form m_XXXXXXXXXID contains a foreign key to another table in the DB. So basically what I get now is rows with a whole lot of numbers. It's exactly what's in the Assets table:
ID_Asset CategoryID CustodianID ManufacturerID SignedOutToID
1 17 23 14 5
What I'd like to know is if there's an easy way to display the text fields that I've linked to with all of those foreign keys:
ID_Asset CategoryName CustodianName Manufacturer SignedOutTo
1 Soda - Diet John Coca-Cola Fred
I got a text box and a panel.The textbox is at the bottom, and the panel is above it, making a open white space above it.The thing I want, is that when i type "run" into the textbox.The empty space should start displaying messages of its actions.Just like in command prompt.If you open a cmd window. (make it small) then type in "ipconfig" (as an example), the text that shows up, makes the scroll bar, follow it down.
View 2 RepliesI am using the code shown below to compare two Access databases with two fields each and write the results to a third Access database. I am getting an error at the "Do While DMReader02.Read = True" line: "Invalid attempt to call Read when reader is closed." Why would the reader be closed at this point if I am using different DataReaders in the two loops?
Imports System.Data.OleDb
Partial
Class Form1
[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.
My Application ( Vb.Net) is to scan Access DB forms and find out the Activx control if present and it works fine. But my problem is.In some DBs we have tables with mapping path to specific locations (Table Property->Linked Table Manager) and when we relocate these DBs then we need to change the path manually otherwise it will show a message to re-link ( Access DB message) while opening the DB. And I am facing same problem while scanning through my Tool as well and my process stops, continue only by manual intervention.
Do I capture the massage event and send some user specific message to user in the Log file or Report and continue scanning further?
I have a simple Entity query:
Dim rhcexists = From p In dbContracts.Signatures _
Where p.StudentID = people_code_id _
And p.ContractType = "rhc" _
Order By p.ID Descending _
Select p
I then check whether one of the result values is more recent than six months ago using an if..then like so:
If rhcexists.First.SignatureDate > Date.Today.AddMonths(-6) Then End If
However, if there are no results returned this will return an error. Is there a way for me to tell it to act as if the date is older than six months if there is no value at all? e.g., could I in pseudo do something like:
If Exists(rhcexists.First.SignatureDate, Date.Today.AddMonths(-8)) > Date.Today.AddMonths(-6) Then End If
Now I need to avoid exception error for when I move, minimize and close any of the other 3 forms for the program I am building. ZOrder?. I was thinking of using an if statement to determine the zorder of each form. I need to know how to implement the if statement.
Option Explicit On
'Route User to the desired page
Public Class Form1
[Code]....
I need two class libraries that reference each other.Why? One is compiled in C# and the other in VB.NET. It would be better if I could somehow merge the assemblies programmatically, without requiring external programs or even the extended framework.
View 1 RepliesI have a report that i'd like to display an Image for each record. But not all records have an image. The problem I have is that the last image is then repeated in the next record.
I would like to know how to have any empty field display a default image.
Code I have in report
Private Sub Detail_Format(Cancel As Integer, FormatCount As Integer)
Me.Image21.Properties("Picture") = Me.PhotoLink
End Sub
Photolink is a textfield and Image21 is an Image.
i have create a setup file with inno software including interop.MessengerAPI.dll of chatting application(with windows live messenger).I have created a setup file with inno of that chatting application.but installed that setup it is work in only my pc it is not work in anather
[Code]...
I am trying to make a program in Visual Basic 2008 Express edition which have a textbox where the user can write information to search for in a simple database stored in the program-code.
What I would like is that when the user types a word, a string variable connected to that textbox.text will be treated as a string. BUT if the user types a number in the textbox, the textbox.text will be treated as an integer (for example a "Double")
i have create simple chat application with windows live messenger.I have give reference of essengerAPI type Library.then it works.after creating a setup file with inno software including interop.MessengerAPI.dll of chatting application(with windows live messenger).Install that setup on anather machine then following errors are generates. ( Error HRESULT E_FAIL has been returned from a call to a COM Component).How to avoid or remove this error.?The chatting is not done in windows live messenger.I have give the anather reference ie, Interop.MessengerAPI.dll but same errors will be generates.Interop.MessengerAPI.dll it is supported in windows xp or not?
View 1 RepliesI'm searching for a solution to resize image(jpg) being passed in from an array in Picturebox Control on .NETCF 2.0 in VB.NET without resorting to using the opennetcf library, is it possible?
View 1 RepliesI am new to VB.Net and was using VB 6.0 for the last 10 years. I am having some difficulty in accessing fields and changing these.[code]...
View 4 RepliesI'm trying to pull all records and fields from a MS Access table. My fields are: numOne, operator, numTwo and result. I'd like to display those fields in a listbox as the following output: 1(numOne) +-/*(operator) 2(numTwo) = 3(result) or simply 1 + 2 = 3. I was able to get some coding going. The problem that I have is that I'm not finding a way to add the fields on the same line, since I can find the right syntax to have all fields added together.
Dim ConnString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:UsersLeo DaCostaDesktopAPUVB AdvancedDaCosta Weeks 5-6MathOp.accdb"
Dim mySelectQuery As String = "SELECT * FROM MathOp"
Dim myConnection As New OleDbConnection(ConnString)
[code]....
How do i find out the number, names and datatype of fields in an Access table
View 16 RepliesI am trying to enter a record into an Access database via visual basic programatically.I had this working fine when I had the datagrid bound to the database but now I have decided to do it all at runtime to save on resources at runtime.When I unbound everything and tried running it with my existing code
Try
ds.Tables(
"tblProduction").Rows.Add(row)
[code]....
This is the line of code that has to have another 30 entries in it.
Does anyone know how to sum fields in ms access using SQL and then place it in datagridview? I have a ms access table with fields 'Points' and 'FacultyID'. I would like to know how to sum all values on 'Points' field and place it in datagridview. Also, I would like to know how to filter values from 'Points' based on selected 'FacultyID'.
View 1 Replies