I have a date field (smalldatetime) in a table and in particular cases I need to set the date field to null. Currently, when setting the sqlparameter.value property to a date
endDateParam.Value = "5/15/2011"
the field is updated with the proper date. However, setting it to
endDateParam.Value = System.DbNull.Value
[code]....
How to check whether a column is null i use the following code but I got this error "Input string was not in a correct format."
[Code]....
When I put a break point to the last if clause in the sub ("If (backOrder < 0) Then", see below) it runs until the break point, if I put the break point further below, I get the following error:
Cannot insert the value NULL into column 'OrderID', table 'WHM.dbo.OrderDetails'; column does not allow nulls. INSERT fails. The statement has been terminated.
I've discovered first hand that it only happens when prodqty is bigger then qtyOnStock, thus executing the if clause.
The code:
Private Sub NCOSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NCOSubmit.Click
Dim sqlText As String = ""
[Code]....
I am trying to create a treeview in VB.net, the data has to be loaded from MSAccess 2010 database. When I try to run this program I get error : Argument Null Exception was unhandled, 'column' argument cannot be null and the program crashes. I have pasted the code as under:
Imports System.Data.OleDb
Public Class frmRating
Private Sub frmRating_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles
[code].....
In a WinForms app (VS2008 / .Net Framework 3.5) I bind data from SQL Server to controls. If there's a null value e.g. an employee has no middle name (allowed by business rules), when I browse that record at runtime an exception is thrown. So I code: If Not (row("middle_name") Is DbNull.Value then txtMiddleName.DataBindings.Add(New Binding("Text", row, "middle_name)). Say someone adds a middle name to this record, because the control had no databindings the dataset.HasChanges property is false and update stored proc doesn't run. I guess I could handle this like this: If txtMiddleName.Databindings.Count = 0 AndAlso txtMiddleName.Text <> "" Then row("middle_name") = txtMiddleName.Text. I guess I would have to do something similar to handle a value changing from not null to null.
View 8 Repliesi'm working with a database application and i want to check if there is a null value in a specific column but it works only when its not null but if its null it throws an exception automatically
i tried to change the nullvalue property of this column but i'm not able it shows a message that its not a valid property
i tried to change the source code in the code editer but it changes back automatically
I have a databound DataGridView and use a button to control updates.
The problem is that if a db Column does not allow a null value an error is thrown ("Column <ID> does not allow null values") and then the datagridview automatically removes the row. This error is raised as soon as the user leaves the cell and before the update command is issued.
I'm working with a database application and i want to check if there is a null value in a specific column but it works only when its not null but if its null it throws an exception automatically. I tried to change the null value property of this column but I'm not able it shows a message that its not a valid property. I tried to change the source code in the code editor but it changes back automatically. Is there a way that I can work around this?
View 5 RepliesUsing VS2005, VB.Net, Dot Net 2.0, SQL Server 2000. If have some Columns (varchar and numbers) in a DataRow that I want to set to DBNull in the database. The fields as defined as Nullable in SQL DB table.
I have some fields that are populated when loaded but I want to update to be null using the ADO.Net data objects. If I try and use Row("FieldName") = DBNull.Value a 0 gets written to number fields (not sure what gets written to varchar fields.) What code should be used to update fields to Null using ADO.Net dataobjects?
[Code]...
I am using VB.net within Visual Studio 2008. I currently have GridControl where one of the columns fetches a real number from the database. Whenever I try to remove the value I get a red 'X' saying that the input string is not the right format even though I know it can display null because the row underneath fetched a null value for that column.
View 1 RepliesI am using VB2008 on Win XP SP3 and an relatively new using this language. I would like orientation or advice on how to proceed given the following:I execute an SQL statement, such as select * from MyTable where FieldX='aaa'An exception happens. Now I need to attempt to determine what went wrong:1. Cable was cut2. Syntax error in SQL3. PC where SQL Server is running crashed4. Timed outI need to attempt to recover from this issue. I have basically 2 options: It is a glitch that self corrects after a period of time, so I can just go ahead and retry the operation a few times. Option 2: It is something permanent, so no matter how many times I retry, the error will persist.
View 3 RepliesI've using binding source filter to filter the data i see in the datagrid based on the value of the cell (this is in relation to the checkstate of a checkbox column), so far so good
InvBindingSource.Filter = "Saved = '1'"
what if i wanted to filter and only show the rows with null in that column?
I am selecting the max value of a column from a table. If the table does not have any rows i need the result as zero. how can i achieve this
View 6 RepliesI am currently working on an SSIS package that we are migrating from SSIS 2005 to SSIS 2008. The issue is that the developers of the current version used the fact that in SSIS 2005 the accessor of a NULL column returns 0, whereas SSIS 2008 throws an exception. Also, they extensively use expressions such as this one:
IIf(Row.X_IsNull, System.DBNull.Value, Row.X)
The problem is that in SSIS 2008, regardless of whether the condition is set to true, the program still tries to read Row.X and throws an exception. The package is big and it would take a very long time to convert all of these IIfs to manual Ifs with temporary variables.
With a Decimal, I use:
document.Air1 = CDec(IIf(Decimal.TryParse(Air1TextBox.Text, Nothing), Air1TextBox.Text, "0")) to fill the column with there is no value.
I would like to do something similar when the date is blank (preferably with NULL or just plain blank):
document.TestDate1 = CDate(IIf(Date.TryParse(TestDate1TextBox.Text, Nothing), TestDate1TextBox.Text, " - - ")) - of course, this throws an exception.
The table Data Type is date.
I am connected to a MYSQL database and the following Insertcommand works fine:
InsertCommand="INSERT INTO suppliers (Supplier) VALUES (?Supplier)"
Now when I want the option of updating all the columns it keeps saying "Column 'Contact_2' cannot be null" or contact_1, so all the fields need something and not all suppliers of course have two numbers. What am I doing wrong? here is the
InsertCommand="INSERT INTO suppliers (Supplier, Contact_1, Contact_2) VALUES (?Supplier, ?Contact_1, ?Contact_2)"
I have a smalldatetime column in SQL that can have a null value, but when I try to insert a null value using SqlTypes.SqlDateTime.Null and LINQtoSQL it puts in 1/1/1900 instead of NULL.
What is the best method to insert a null, or am I doing it at the moment. If I am using the correct method at the moment, what should be done to prevent the 1/1/1900 being displayed on my fields in a WPF application.
I have problem trying to update a single column. I initially insert an null value,
Here is the insert code..
CODE:
I have a datagrid view in my vb.net application. I want to update this DataGrid View so it shows any changes to the database (More specifically when a Column is added). I have tried
DataGridView1.Update()
I have a bound datagridview when a editing a datagridviewtextboxcolumn and the end edit is called I use the tableadaptermanger.updateall(dataset) to update the db. All well and dandy but having a problem with a comboboxcolumn. The db is only updated after I have selected a new value from the comboboxcolumn and click on another cell in the grid. If I dont click on another cell the db is not updated. I have tried this code but no good:
[Code].....
vb.net 2005
Here is one attempt:
Dim myRow As BurnerService.OEBSContractBatchesRow
Dim myDate As Nullable(Of DateTime)
myRow = Me.BurnerService.OEBSContractBatches.AddOEBSContractBatchesRow( _
[Code].....
My program creates columns at runtime with the following code:
Cmd = New OleDb.OleDbCommand("ALTER TABLE [Parent] ADD [" & ColumnDate & "] int", con)
objCmd = New OleDb.OleDbCommand("ALTER TABLE [Parent] ADD [" & ColumnDate & "] int", con)
objCmd.ExecuteNonQuery()
I add data into the newly inserted column with the following code:
da.SelectCommand = New OleDb.OleDbCommand(sql, con)
Dim cb As New OleDb.OleDbCommandBuilder(da)
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
ds.Tables("SchoolMaticsDatabase").Rows(inc).Item(ColumnDate) = Hours * Num
da.Update(ds, "SchoolMaticsDatabase")
All of the above works fine; the issue arises when I try to edit the information originally placed in the newly added column. These are the approaches that I have taken. (None of them give an error message; it simply won't update within the database.)
da.SelectCommand = New OleDb.OleDbCommand(sql, con)
Dim cb As New OleDb.OleDbCommandBuilder(da)
cb.QuotePrefix = "["
[code]....
I added a column to the table manually via opening the access database and all the above approaches work for editing data stored in that column. So I believe it is something to do with the fact that the columns are created at run time.
i am developing an application in VB.net implies some datagridview operations. the appl contains one DGVW with columns fixed programatically, one such column is Datagridviewcheckbox column. the datasource for dgvw is bounded by a datatable. the user needs to enter the values in the GUI.
supposing the user enters the 2x2 matrix values, and the user checked the checkbox last cell in the dgvw. The problem - the last cell value is not updating inside. if ii debug through code, the "cell(2,2).value" reurns null value whereas the rest of them returns the value what i entered.
if i clicked the mouse some where in the dgvw after entering the last cell value, then it is returning the exact value as expected.
I have setup a datagridview with one column as a combobox and bound to a dataset.
However, during runtime I want to refresh that column to show the changes. How do I do that?
I need to sort a DataTable or DataGridView by a column that is a string value, but with null/empty values at the BOTTOM when sorting ASCENDING. The DataTable is NOT populated by a SQL statement, so no order by. If I do
[Code]...
I have a database and I'm storing images in it along with a person's name, and other attributes. I've databound my listview with a stored procedure. I want to know how I can display an icon on a row depending on if the record for that row has a picture or not for the person...I'm not sure how to accomplish this however with the templates in asp.net
EDIT:
Here is my template and the s where I'm hoping to put them.
<ItemTemplate>
[code].....
I need to sort a DataTable or DataGridView by a column that is a string value, but with null/empty values at the BOTTOM when sorting ASCENDING.The DataTable is NOT populated by a SQL statement, so no order by.If I doDataGridView1.Sort(New RowComparer(System.ComponentModel.ListSortDirection.Ascending))then it throws an exception, saying that the DataGridView is DataBound, which is correct, but doesn't help me, and I want to keep it databound.
View 2 RepliesI have a databound DataGridView, and I'd like to keep one column in front, with a slightly smaller width than the default. The grid's AutoSizeColumnsMode property is set to Fill so that the columns fill out the entire grid. This makes the first column equally large as all others, which is why I need to set its width manually. The smaller column is the first one with the checkboxes. I have two grids that I need to do this with, and for some reason it works just fine with the first grid, but gives a null reference error on the second grid...
Here's the code for the first grid (working fine):
vb.net
Public Sub UpdateTodoGrid()
' Load todo items
todoGrid.DataSource = _TodoManager.LoadAll()
' Set backcolor
For Each row As DataGridViewRow In todoGrid.Rows
[Code] .....
As you can see, the code is exactly the same (except for not setting the BackColor of each row and not using the ReadOnly property*). When I run this code, it gives me a null reference error ("Object reference not set to an instance of an object.") on the line where I set the column's Width. Obviously 'col' is not Nothing (otherwise it would have errored before that line), and there's nothing else there that could be Nothing... I assume that something happens internally in the grid when you set the width of a column, and that there is a null reference there, but obviously I have no control over that.
The grid's are absolutely the same, as the second grid is just a 'copy' (meaning I copy/pasted it in the designer) of the first. So all their properties are equal. I thought maybe the ReadOnly properties were the problem, but I tried putting them in in the same way and the issue did not go away... The first grid is not ReadOnly (because the checkboxes need to be editable), but all rows except the first are, while the second grid is completely ReadOnly.
I have written the following lines of code
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.OleDb
[code]....
When I run the program, it comes back with the error message
Invalid column name 'testtx2'
I perhaps need to add that s_name is a valid field name in the customer table.
My program creates columns at runtime with the following
Cmd = New OleDb.OleDbCommand("ALTER TABLE [Parent] ADD [" & ColumnDate & "] int", con)
objCmd = New OleDb.OleDbCommand("ALTER TABLE [Parent] ADD [" & ColumnDate & "] int", con)
objCmd.ExecuteNonQuery()
I add data into the newly inserted column with the following
da.SelectCommand = New OleDb.OleDbCommand(sql, con)
Dim cb As New OleDb.OleDbCommandBuilder(da)
cb.QuotePrefix = "["
[code]....
I added a column to the table manually via opening the access database and all the above approaches work for editing data stored in that column. So I believe it is something to do with the fact that the columns are created at run time.