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 have a populated datagrid that has some fields that are needed for calculation in my app. In the dataset they are set to Allow DBNull False because I can't have a DBNull in my calculation for obvious reasons. I have found answers to incorrect data entry and blank fields in these critical fields (see code block below), but they only work if some data is entered somewhere in the new record, even if I populate the field with default values other than <DBNull> on adding a new row. If a user doesn't add any information and just tabs through a new record/row or cursors down the app blows up. If they cursor up without entering any data, the blank field procedure for these protected fields engages fine.
View 12 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 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 am receiving this error on this line
ctl.Value = CType(Me.Value, DateTime)
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 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 _
[code]....
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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I've got the following LINQ Statement:[code]invRecord.Pack_Num is a field of type Integer. This means that when I try to access it, if it is DBNull I get a StronglyTypedException. The above code throws this exception. If, however, I remove the "invRecord.Pack_Num = PSNum" and in its place put something like "True", the code works fine. So I guess my question is, why is that that invRecord.IsPack_NumNull() returns False when the value is in fact DBNull and what can I use as a conditional instead? I've been beating my head against the wall for a while now and I can't find a solution to this problem.
View 1 Replieshow to set a field in a dataset table back to <DBNULL>?
View 4 RepliesThis code is supposed to return all the records where the month component of the DateCreated is equal to the specified MonthIssued value. The problem is, if DateCreated is DBNull I will get a runtime exception which requires the extra If ternary operator. Any way around this / will this cause a performance hit the code is actually executed?
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I am using a dataset to pull data from a DB. One of the fields in a row is NULL. I know this. However, the following vb.net code throws a StrongTypingException (in the autogenerated get_SomeField() method in the dataset designer):
If Not IsDBNull(aRow.SomeField) Then
'do something
End If
According to documentation and this question it should be fine.
Attempting to load datagridview and getting error Conversion from type DBNULL to type Date is not valid.SQL Field type is datetime but is sometimes NULL. When displaying records in grid, I need the NULLS to display as blanks and not 1/1/1900. I also need the dates to display in user's windows regional setting format.
View 2 RepliesI am recieving this error on this line
ctl.Value = CType(Me.Value, DateTime)
Conversion from type 'DBNull' to type 'Date' is not valid.
I am using Data Grid View and This is a calendar Type Column
I have this problem that when the textbox don't have a value I always get this error "Conversion from type 'DBNull' to type 'String' is not valid." [code]...
View 1 RepliesI am receiving the following error "Conversion from type 'DBNull' to type 'String' is not valid" when checking a textedit control to see if it is empty or more than 1 characters in length.
Public Class CustomValidationRule
Inherits ValidationRule
Public Overrides Function Validate(ByVal
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I am attempting to convert a DBNull value to a decimal (0, 0.0, 0.00 etc).
My current code is If row.Item("Name of row") Is DBNull.Value Then NameOfRow = Convert.ToDecimal(0.0) End If When i run my app i pass in the row to convert. Every other datatype works/runs as expected except Decimal. It runs with the abbreviated code below:
For each row..in dataset.rows Object = row.table("Table").Item("Name of row")Next The Object.... line causes an error. The error is DBNull' to type 'Decimal' is not valid.... Ive tried many attempts to overcome this but cant get this to work. Could anyone guide me?
Im using VB in VS 2005.I have found several methods of testing if a value from a dataset is null. Are there differences between these two ways of doing it:
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Is one faster than the other? From some searching online, there seems to be debate about the best way to handle null values.
I've got the following LINQ Statement:
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invRecord.Pack_Num is a field of type Integer. This means that when I try to access it, if it is DBNull I get a StronglyTypedException. The above code throws this exception. If, however, I remove the "invRecord.Pack_Num = PSNum" and in its place put something like "True", the code works fine. So I guess my question is, why is that that invRecord.IsPack_NumNull() returns False when the value is in fact DBNull and what can I use as a conditional instead? I've been beating my head against the wall for a while now and I can't find a solution to this problem.