Set A Dataset Field To DBNULL?
Oct 12, 2011how to set a field in a dataset table back to <DBNULL>?
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Check For DBNull In SQL2008 Data Field?
Jun 30, 2010I'm using VS2010 and SQLServer 2008. I'm trying to test for DBNull in datafields, but every formulation of a test I have imagined (or found) throws an error. Specifically,"The value for column 'ColumnName' in table 'TableName' is DBNull." (system.data.strongTypingException).Well, not too helpful. I know it's DBNull, and I want VB to recognize this.Here is what I've tried so far (all with the same result).
[code]...
DBNull When Using LINQ To DataSet
May 20, 2010I'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 RepliesDifferent Ways To Test DBNull From Dataset
Oct 6, 2009Im 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:
[code...]
Is one faster than the other? From some searching online, there seems to be debate about the best way to handle null values.
Getting Error With DBNull When Using LINQ To DataSet
Nov 12, 2011I'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.
LINQ To Dataset - How To Handle DBNull
Jan 29, 2008This is what I'm doing to select and display 3 columns of my datatable in GridView:
Dim myCustomers = From Cust In myDataset.Customers _
Select CustomerId = Cust.CustomerId, _
CustomerName = Cust.CustomerName, _
ExpiryDate = Cust.ExpiryDate
DataGridView1.DataSource = myCustomers.ToList
The expiry date has null values in many records whose expiry date is not set.On executing the query I get runtime error:System.Data.StrongTypingException "The value for column 'ExpiryDate' in table 'Customers' is DBNull."
Obviously, my LINQ query is wrong or incomplete, but I am not able to figure the way to do it correctly.
VS 2008 : DBNull In A Dataset.Delete Statement?
Nov 3, 2010I am trying to work programmatically with a dataset. The tableAdapter was created by dragging and dropping the dataset on my form, and then deleting the binding navigator and dataviewgrid. The problem I am having is when I am trying to delete a record that is DBNull. The dataset.delete( ) call creates fields for each of the fields, along with their data type (say Description as String). but I get an error whenever the field has a DBNull value.
CourseTableAdapter.Delete(DBDataSet.Course.Item(1).CourseID, DBDataSet.Course.Item(1).CourseDescription)
The error is Throw New Global.System.Data.StrongTypingException("The value for column 'Description' in table 'Course' is DBNull."I do have Option Strict On, but the problem exists even if I turn it off.
Conversion From Type 'DBNull' To Type 'Decimal' Is Not Valid When Field Has Data?
Feb 7, 2012I am pulling data from a local MSSQL database using a stored procedure, then send the data to a web service. Every part of the component works well except for a pesky problem will a DBNull being returned from the DataRow field, when I know that the field is not null and has valid data. The database and associated INSERT statements that add to this field are designed to not allow NULL entries. When I debug break the program on or right before the line that throws the error I see that the field has valid data for the current row.If I add a null check to the code (as below) the operation continues as normal:
Dim dataResultsTable = Me.myViewTableAdapter.GetData(int)
For Each myDataRow In dataResultsTable.Rows
If worker.CancellationPending Then
[code]....
Why is the read operation returning DBNull instead of the data in the database?
EDIT: Just to be clear, the operation does return the proper data, but the data is not being saved into the variable.
Assign A Value To A Field In DataSet?
Jul 7, 2010I want to assign a value programatically to a field in current DataSet which is not bound to any control on the form. I am using the following method but it does not save the value "F" in DB on calling UpdateAll command.
Me.WorkOrderDataSet.Orders.status1Column.DefaultValue = "F"
My update command:
Try
Me.Validate()
Me.OrdersBindingSource.EndEdit()
[Code].....
Dataset Field Not Able To Contain Enough Information?
Mar 7, 2012So I have a form that uses a datagrid with checkbox selections for multiple (read as many!) items.When I click a button labeled "Save to file", all the information on the form, to include the values of the selected datagrid items are then saved to a database. It works great most of the time.However, I have found that if I select more than 3 items in the datagrid, I get an error pointing to the data set and data adapter stating "OleDbException was unhandled - The field is too small to accept the amount of data you attempted to add.Try inserting or pasting less data".The code it points to is:
da.update(ds, "TrainingRecords")
In the dataset, I have tried to change the max length of the associated field.It was set at 255, and as long as I stay under that, I seem to be fine. But if I go over it, I get the error. I can change the design I guess to make it less wordy and therefore store less data, but is there an easier way?
DataSet From XML (missing Field)?
Aug 21, 2011This is the XML output of my command in a web browser.I need to get the MachineID value.
<?xml version="1.0" encoding="UTF-8" ?>
- <Response>
<Code>0</Code>
<Message>OK</Message>
[code]....
Reading A Field From A Dataset?
Aug 18, 2011- Below code is in the LOAD form event.
- Within TMEMBERS table there is a TOTAMT field.
- Question is: What is the code to read TOTAMT field as I need to do some calculations as part of the LOAD event in this form. Not sure how as this was generated by the dataset wizard and not the tipical Dataset manual definitions.
'TODO: This line of code loads data into the 'DsMP.TMEMBERS' table. You can move, or remove it, as needed.
Me.TMEMBERSTableAdapter.Fill(Me.DsMP.TMEMBERS)
- calculation lines will be here.
Get Field Value From Typed-dataset Vs Current?
Mar 16, 2010I am using Dataset created by the wizard with BindingSource and Binding Navigator
For example, I placed a Textbox on the form, and bind it to a field.
I was trying to compare the field value stored in the sql server database with the data I have on my form.
Let say I run the form, and Textbox1 get it is value from the first row in mytable from BindingSource (let say value 1000) [code]...
Access Or Update A Field In Underlying Dataset That Is Not Shown On A Form
May 11, 2012I have a Windows Form application with a form that has an underlying data set. When the users click a particular button, the code clears some fields on the form but also is suppose to update a value in the underlying dataset on a field that is NOT displayed on the form.
In VB6 and VBA this is very easy to do. I simply says Forms!formname!NameOfUnderlyingFieldNotshown and pass it the value. How do I do this in VB.net with a Windows Form and underlying dataset?
Disable Bound Field From Editing Dataset Until Save Button?
Nov 17, 2009On my form i use binding source bound to fields.. if a user starts to change something then hits cancel (i set all the fields to "" to clear them) and then if they choose that record again it shows nothing in the bound fields..
is there a way to reset/cancel from editing without loosing original values?
"Conversion From Type 'DBNull' To Type 'Boolean' Is Not Valid" After Checking That It's Not DBNull
Jan 18, 2012In my ASP.Net Web-Application, I'm getting this error: Conversion from type 'DBNull' to type 'Boolean' is not valid.
[Code]...
Dataset Link To Database - Add One Field Inside The Database
Jul 2, 2009I had a dataSet which link to a database. I need to add one field inside the database, After adding the field, how can I update and link it to the dataSet?
View 4 RepliesCheck If A Field In A Data Table Is Null Before Creating A Textbox Bound To That Field?
Feb 24, 2010I 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.
View 8 RepliesMake Gridview Checkbox Field Update Boolean Field In Database?
Feb 7, 2011There are lots of questions about this but I've not been able to solve my problem using the answers to any of them (after many, many attempts..)
I'm working in vb.net creating an asp.net web application. I have an SqlDataSource and a GridView on my page.
I want to change the DoNotMail boolean value represented by a Gridview checkbox and automatically update in the database if the checkbox is checked from 0 (False, Will Mail) to 1 (True, Won't Mail) here is the code I used. [code]...
is it possible to do a two way sync on the entire gridview when the user hits a button so you don't have to do an update every time a row is changed? because the user might check the box and then check another box then uncheck a box and it would be a lot of updates...
Make Database Field A DateTime Field Currently Is Set To String?
Oct 5, 2010Dim query as String = "Select * from openquery (devbook, 'SELECT wb.arrival_time FROM web_bookings wb ')"All I need is to convert my arrival_time into a datetime field in the query
View 1 RepliesRename Field Headings And Change The Field Type?
Jun 28, 2010I am trying to edit a dbf table. I would like to be able to rename field headings and change the field type, ie string or dbl, and the size of the field. is this possible to do with vb.net. I have connected to the dbf file but after that am lost on what to do.
View 3 RepliesCan't Get Rid Of DBNULL
Dec 13, 2011I 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
[Code]....
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.
DBNULL Error In .NET?
Nov 9, 2011I am receiving this error on this line
ctl.Value = CType(Me.Value, DateTime)
Handling DBNull In Dot Net?
Jan 19, 2012I 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.
[Code]...
How To Set A Double To DBNULL In .net
Mar 10, 2010Dim 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.
If Syntax For Dbnull And Value?
Nov 12, 2009I need to make something like :
if isdbnull(value) or value = something then
'do something
else
[code].....
Replace DBNull With Zero?
Sep 29, 2009So 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 Replies'DBNull' When Searching A DataGrid?
Dec 21, 2011I'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].....
.net - Filtering DBNull With LINQ?
Mar 8, 2010Why 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?
Asp.net - Correctly Check DBNull In VB?
Jan 13, 2012Why 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.