Dim k as nullable(of double)I am INSERTING a rec in database containing K (sometimes it has some value otherwise a null) It works ok.But when i UPDATE a rec and assign a field the value of k and when k is NULL
it gives me an error that you cannot assign a NULL , you should use DBNULL.But i think DBNULL.value can only be assigned to an object not to double.
I updated an MS Access file with data and it showed the data is there. When I tried to retrieve I get this message " Conversion from type DBNULL to type Double is not valid" Below is the code to retrieve.
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when a user inputs a value into a text box, i am searching that value in my dataset.although the number that i entered is in my dataset, i am getting this excemption.
View 3 RepliesIn my ASP.Net Web-Application, I'm getting this error: Conversion from type 'DBNull' to type 'Boolean' is not valid.
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I have a situation where I am handling both single & double mouse click events on a form. In both cases something has to be loaded, however when a double click occurs, I do not wish to execute the code attached to the single click event.Is there a way to intercept the mouse click's and check if double or single and then execute the right event appropriately?
View 2 RepliesI have a htpc project that I am working on. The main program loads dll plugins which are basically other win forms. On each of these forms, including the main program, I use a picturebox (a double buffered picturebox) for the background image and then draw everything on it by hand. Whenever I load the form from the dll and show it, I get a weird flicker. It looks like it is the previously used double buffer. Is there any way to clear the background double buffer before the flicker? Or am I going in the wrong direction?
Here's a couple of videos of the problem:
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Notice the black screen with the white lines on it or the flash of the desktop after I click "Movies." How do I get rid of that?
For greater accuracy I should use a Decimal instead of a Double ( so I've been told ). Why then have Microsoft chosen to use DOUBLE for most of the functions that return a floating point value in the Math Class?
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In vb.net, im using objWriter.Write("playerA= "x"")as you can see im using double quotes inside double quotes, how do i skip it so the error doesnt show up?in php you make an "" to skip the string like ("playerA = "x" ")
View 6 RepliesWhen i use VB6 i get the following outputs
961.605 * 100 = 96161
936.495 * 100 = 93650
929.295 * 100 = 92929
NOW..... When i do the above in vb.net 2005 i get the following
961.605 * 100 = 96160
936.495 * 100 = 93650
929.295 * 100 = 92930
How can i get the same output as the VB results. And i have tired it ! Type conversions, math functions, everything i can think of to get the same VB6 output !
When i use VB6 i get the following outputs
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I've asked this question before, and so have many before me, i have done extensive research on the topic and stil no help. Maybe this is some kind of secret info. shared only amongst top programmers. Bt how do you really, trully double buffer a form, aside from setting "Double Bufferd" to true, which doesn't work in most cases, I want to know how do companies lyk Microsoft and Symantec, prevent flashes on big applications such Word and Norton.
View 4 RepliesIf I try to display a command line argument that has double quotes around, the double quotes are always stripped off. How can I avoid this?
for example, the argument is "c:xx.txt" and this displays c:xx.txt instead Console.WriteLine((My.Application.CommandLineArgs(4)))
I am teaching myself vb.net with visual studio 2010 and i have ran into a wall. I have a datagrid on my form that shows all of my customers that are in the dataset that was created in access 07. I have a search bar and check boxes to select which column name to search in. Whenever I search it throws up a strong typing exception,
System.Data.StrongTypingException was unhandled by user code
Message=The value for column 'PickupTime' in table 'CustomerRouteTable' is DBNull.
Source=EXBSTESTDatabase
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I think this means that there is nothing in the field, but this is a field that nothing should be in. If i comment the throw exception out it moves on to the next one that has nothing in the field. I tried just putting 0's in all of them but it still gives the same exception.
I have a CSV file where the values are in double quotes and seperated by a comma. I'm getting incorrect data if I try to seperate the string with my Split function. How do I do it?
Example:[code...]
I've been just making random programs trying to get the hang of the new language this time I was making a leap frog game where it switches back and forth beetween frogs every time a button is pressed. It also checks if the frog can land in the text box above the button pressed, if there is another frog there a message box will pop up saying sorry space is filled other wise the frog should land there.
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The error message says "Conversion from string "frog1" to type 'Double' is not valid." I understand what a double is but I've tried And If and that causes a bunch of errors.My Question is whats wrong with this cod and how can I make a double if statement???PS I did try to make an array to shorten this but thats in a different fourm will post URL later
I am receiving this error on this line
ctl.Value = CType(Me.Value, DateTime)
I have been having an error that DBNull cannot be returned as a String and after hunting around I came up with the folowing but have had no sucess. it is very inportant that this code can handle DBNull as it will encounter this often.
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I need to make something like :
if isdbnull(value) or value = something then
'do something
else
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So I'm importing Excel data using ADO into a DataTable then pushing out to an Access DB. A couple of the Excel columns have several blank cells that I would like to change to a zero before pushing it out. How can I check/change the DT null values to zero? I've done some searching but was wondering if I could do it without a loop.
View 3 RepliesI'm writing a program for my friend as a gift. He's a movie lover, and has this Excel spreadsheet with all the movies he's watched in it. I converted the spreadsheet to an Access database,then used that database in my program. I've been going by the example in my textbook (Programming with Microsoft Visual Basic by Diane Zak), and everything been working until I put in a "Find Movie Title" button. I want to be able to search the column "Movie Title" for a title input by the user (whether it's the whole title or just a few characters)Here's the code:
Private
Sub btnFindTitle_Click(ByVal
sender As
Object,[code].....
Why does the following query raise the error below for a row with a NULL value for barrel when I explicitly filter out those rows in the Where clause?
Dim query = From row As dbDataSet.conformalRow In dbDataSet.Tables("conformal") _
Where Not IsDBNull(row.Cal) AndAlso tiCal_drop.Text = row.Cal _
AndAlso Not IsDBNull(row.Tran) AndAlso tiTrans_drop.Text = row.Tran _
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Run-time exception thrown : System.Data.StrongTypingException - The value for column 'barrel' in table 'conformal' is DBNull.
How should my query / condition be rewritten to work as I intended?
Why does the following code: A = not IsDBNull(CurRow("BuyBook")) AndAlso CType(CurRow("BuyBook"), string) = "Yes" results in the following error:
Conversion from type 'DBNull' to type 'String' is not valid.
I am writing a program that pulls data from a database.For each table that I pull data from, I write a series of If Than Else Statments to catch any null values and assign Nothing so as not to throw an exception.Is there a way to check against a DBNull value without writing an If THan Else Statment for each column I am pulling from the database?
View 7 RepliesI have simple app code:
Dim sw As New StreamWriter(FileName, False, System.Text.Encoding.GetEncoding(Encoding))
Dim adapterPositions As New MyDatabase1DataSetTableAdapters.PositionsTableAdapter
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How I can check column is DBNull or not?
Is it possible to converty a type System.DBNULL to a string type?
View 3 RepliesI wants to ask how to convert DBNull to Date type?
For Each row As DataRow In dt.Rows
i = 0
Dim array As Object = row.ItemArray
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array(i + 10) is datetime type, in the program above, if the Datetime column contains items, it still can run. However, when it loops to a row where the Datetime column does not have value of datetime (or the column is null), then an error " Conversion from type 'DBNull' to type 'Date' is not valid" is occured. I tried to use the if statements as program above but it seems like cannot works.
this code i pick from grauva khanna... it working..but for one coulmn only.. my question is ..how to manipulate every column with dbnull.value
'If TextBox1.Text.Trim = "" And TextBox2.Text.Trim = "" And TextBox3.Text.Trim = "" And TextBox4.Text.Trim = "" Then
'DT.Rows.Add(DBNull.Value, DBNull.Value, DBNull.Value, DBNull.Value)
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I have a piece of code im working on and is stuck on Select Sum statement which keeps returning a Conversion from type DBNull to type Decimal is invalid. Below is the code and Im working with a Access Database. Everything works good if the Batch Number exists and its when the Batch Number does not exist.
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I have a form with some textboxes in it. Not all the boxes are mandatory fields. I also have a store procedure that saves the records to the DB. when I try to save a record, I get an error PLS-00306. I am passing the required number of parameters to the sp. When I populate all the fields, the record is saved but NOT when some fields are left blank.
If txtInvoiceRef.Text = Nothing Then
strSQL.Parameters.Add(New OracleParameter("varInvoiceID", OracleDbType.Varchar2, 50, ParameterDirection.Input)).Value = System.DBNull.Value
ElseIf txtPaymentDate.Text = Nothing Then
strSQL.Parameters.Add(New OracleParameter("varPaymentDate", OracleDbType.Date,
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I have a dgv with some checkbox columns. When I load data in the dgv, and I want to check in the cellcontent_click event, whether an another cell value (this is a checkbox cell too) is true or false, I get the error that the operator = is not defined for
dbnull value and for boolean. F.e.:
If
dgvegyenijogok.Rows(e.RowIndex).Cells(3).Value = True
And
dgvegyenijogok.Rows(e.RowIndex).Cells(4).Value = True
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