I 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.
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.
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.
I am creating a form that is able to update data in SQL server after selecting an MS Access file (.mdb). I am having an issue where the data has a single quote ('). I found out that the solution was to use Replace() - to replace the single quote with two single quotes - Replace(string, "'", "''").Now, for some reason, I am getting an error "Conversion from type DBNull to type String is not valid." Here is the code.
cmd = New SqlCommand("Update Child Set " & _ "TopLevelProject = '" & row("TopLevelProject") & "' ," & _
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:
[code...]
Is one faster than the other? From some searching online, there seems to be debate about the best way to handle null values.
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.
This 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.
I am returning to VB and coding after several years of trying to be out of coding :) I would like in grabbing data retrieved from a SQL database call into an array of sorts so that I can quickly close the database connection. I am having some trouble remembering how to do this. Most of the posts I've found say to use the dataSet() functionality, but I do not have a table name for the structure to mimic. I am selecting from several tables on a remote server.
I am using VB.NET 2008 and I want to delete an unused table from the dataset. When I do this I get error messages which seem to originate in the Table Adater Manager on the various forms. The only way I can figure out to correct this is to delete the table from the code after deleting it from the dataset designer. But it says that you shouldn't do this.
I have customer/order form.When i delete a record from datagrid.It deletes the record but when i refresh the page or run the app again it comes because i think it just deletes temp from the grid not from the database.How do delete it from the database?[code]...
I want to know how to use the ASYNC CTP to manage the querying of a SQL Database with a SQL Select statement and use a SQLDataAdapter to fill in a DataSet. I have downloaded the VS2010 SP1 and the ASYNC CTP, I have also reviewed the videos on the MSDN site and the documentation included.
my program is "live" and my customer has troubles because it doesn't functioning as well as it should.I don't know what happen, did I changed something or not but suddenly data won't save to database from newly created forms. Beside this form I have additional 20 forms and everything is working like a charm and I use same code logic to save data to database. I tried to find myself what could be the reason, check by entering data directly to database table (works fine), check insert statement of dataset table (seems fine, too) and everything I could imagine. But now I ran out of ideas and I had to ask here.
Also, I added 3 fields to database table (nvarchar, int and decimal). All 3 of them allow nulls. I changed dataset and data entry form and now data won't insert if I dont enter values to int and decimal fields. Also, this decimal field doesn't accept 0 value if enter but if I assign value 0 from the code than it is ok. I'm not sure if I somehow changed concurrency and somewhere. I tried to find where I can change it but I couldn't find it. I use Visual Studio 2008 and Sql Server 2005 Express. Language vb.net.
I've only dealt with firing a single SQL statement at a SQLServer table and returning a single result... easy....
however....
is there a way to fire a dual sql command and load the results into respective tables within a dataset?.. I'm thinking something along these lines (this code of course does not work)
Dim ds As New DataSet Dim dt1 As DataTable = ds.Tables(0) Dim dt2 As DataTable = ds.Tables(1)
im using try catch to handle this error uponm deletion of record that is foreign key to other table but it seems that my try catch is not working. im using asp.net (VB). can anyone help me???' i want to display an error message in my page.
I am currently teaching myself the caveman code of Visual Basic (VB.net). Apparently I fail at If-statements or something, because I cannot get this to work...
I am having the same problem <as this >> when i update my record in Access Database. It is successfully updated the record in the database. but the dataset in my project is still not updated. I am using vb 2005 to develop the application.
I'm currently trying to delete data from a dataset/datasource/database using visual basic. So here is the run down: I've built a program that can add, delete, and modify customer information from an Access database and I just got the add function working. Meaning, I can now add customers to the database and it is sticking to the database. I re-ran the program and even restarted the computer the computer and the data is in the database. This works fine. However, now I want to get the delete button working but I'm not sure why it isn't deleting some of the fake entries I made just to test out the add feature.Here is the code I am using:
Dim delCompany As UMD3.CompaniesRow delCompany = UMD3.Companies.FindByCompany (NOT SURE WHAT GOES HERE) delCompany.Delete ()
I have a GridView and on a row being deleted I trigger the GridView1_RowDeleting sub, but I receive an error "LINQ to Entities does not recognize the method 'System.Web.UI.WebControls.TableCell get_Item(Int32)' method, and this method cannot be translated into a store expression." Code is:
Private Sub GridView1_RowDeleting(sender As Object, e As System.Web.UI.WebControls.GridViewDeleteEventArgs) Handles GridView1.RowDeleting ' The deletion of the individual row is automatically handled by the GridView. Dim dbDelete As New pbu_housingEntities ' Remove individual from the bed.
I am using UltraGrid for inserting data in table. The problem is that i need to do insert,update, delete with web service. I am getting dataSet from web service and display it into grid but when I do some changes on the grid for example insert or update data, I need also to send new dataSet to web service so that web service do update data.
I'm using Microsoft Visual Studio 2008 to create an application (.VB). The application connects to a Microsoft Access 2007 database. When the user starts the application, the application pulls in the data from the database via the "TableAdapter.Fill" method. The user can then add/update/delete records in the form and those changes are saved and confirmed in the database. The problem is when the user close completely out of the application and restarts it, the modifications that were made and originally sent/saved to the database are wiped/deleted. It appears that the dataset in the application never saves the modifications and when the program restarts it uses the data that was originally loaded into it during the design/build phase of the application.
I am having a problem with the DIM statement. It is saying that it can not convert a DBNULL value to STRING even though there is something in the cell.
I wonder, what is the most elegant way of dealing with the dbnull situation. I have a class, with attribute, let's say: "End_Date", which is being read from database. Type of this variant should be date, but as it's the "End_Date", there might be the situation that something haven't ended yet, and in the database in this field I have a null value.
Right now a deal with the problem this way: Dim mEnd_Date ... Public Property End_Date () Get End_Date = mEnd_Date End Get Set(ByVal value) mEnd_Date = value End Set End Property But I am not sure if that's a good way as I don't declare variants as any datatype?
I am creating a form that creates new users and then updates them to a dataset, I have done this ok, but I am getting a runtime error when I delete a record. Please see below the exception being thrown
"Update requires a valid DeleteCommand when passed DataRow collection with deleted rows"
My code below
CODE:
So I know I need to add a delete command, but how do I write this in code and do I write it in the saveitem click event? I guess I would because the app crashes when I click save to update the dataset.
I am filling a datagridview with a xml file, sorting the grid based on Column 1 then trying to compare a date in Column 4 against the date in a label using the below.
[Code]...
I am entering the date into the grid, example format(30/01/2011) and writing the grid to the xml file.
