IDE :: Handle Null Values When Updating Dataset?
Jun 11, 2009
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.
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Apr 26, 2011
What are NULL values? Sometimes when I try to assign a query to variable, I get error saying:
Type-Cast-Error. txtMiddleName.Text = Reader.GetString(2)
How can I put it that if the value of the Middle is nothing then txtMiddleName.Text = "". Working on VS 2010 (VB.net) EDIT 1: This is the error Message I get (Line 364 is the above mentioned code)
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Jul 17, 2011
On a ASP.net form, I need to add a textbox to update a date field in MS SQL server via stored procedure. I want to verify user input cant figure out the correct syntax to do so (please see below)
If d.Text <> "" Then
cmd.Parameters.Add("@date", SqlDbType.DateTime)
cmd.Parameters("@date").Value = Date.Parse(d.Text)
[Code].....
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Mar 30, 2011
I need to round and print a price like below, but this does not handle null values.How can I handle null values on one line of code? DBRSet is an SQLDataReader and the price is money
<%= Math.Round(DBRSet("price"))%>
I have about 200 .aspx pages of this so I could also use some tips on how to change these in an easy way? Can I do a search and replace with a reg-exp or something like that?
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Jun 22, 2010
I have two Datagrids, One grid has all the customers garments on it with style number and contact length. The other grid has the users who have garment issued to them. the style number is in both grids. I need to loop through the users grid and say if the contract number is 1 from the first grid then the contract date on the second grid will be todays date + 365 days (year contract) I have looked at using a stored procedure and also a for each command but I am just getting stuck with it all. [Code]
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Jan 19, 2009
I read stuff from a SQL DB (database) using a data set. Some of the columns in the DB may contain NULL. I want to go through the table in the dataset and print, or use in some other way, the data. But when I try to use a certain data that corresponds to a NULL in the DB my program crashes.How can I detect - in the dataset - that it has no value and that I shouldn't try to use it?
Private Sub Get�rendenLista(ByVal e As System.EventArgs)
'----------------------------------------------------------------------
' This function fetches a list of �rende from the table �rende
'----------------------------------------------------------------------
Dim cno As New SqlConnection
[code]....
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May 24, 2011
I have some MS SQL field with NULL value. when i am trying to use below in VB.NET code no result comming...
1- dim sqlq as string = "Select * from table where name3 = null and address3 = null"
2- dim sqlq as string = "Select * from table where name3 = '' and address3 = '' "
But if same query # 1 i run direct SQL Query browser it works well.
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May 24, 2009
I've got a subquery that returns the most recent value from a child table. In some cases the subquery returns nothing. The query below fails at runtime because the inferred type of MemberPrice is decimal and is not nullable. [code]...
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Feb 16, 2011
I have run into this problem a few times and have never come up with a good answer. I figure others must have dealt with this already.I have a datareader returned from the database and I want to use the values therein however values may or may not contain NULL. I would like to have a unction that takes in the value from the datareader and returns the value if it is not NULL and blank space if it is NULL.The problem I have is that the data-type of the variable I am testing is variable. It can be a String, and Integer or a DateTime. Can anyone suggest a simple way to test the value and then return the original value (as same data-type if possible) or something else if it is NULL
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Apr 22, 2011
I am using KeyPressEventArgs to restrict several text boxes to numeric entries only. Rather than repeat the code, I thought I would make a "RestrictToNumeric" subroutine and call it from each "KeyPress" event. Like So:
Private Sub txt1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txt1.KeyPress
RestrictToNumeric()
End Sub
[code].....
The problem I am encountering is that the variable 'e' is used before it has been assigned a value, causing a null reference at runtime.
So I tried to add Dim e As System.Windows.Forms.KeyPressEventArgs As?to the RestrictToNumeric sub.I cannot figure out what I need to "Dim" it as...
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Apr 18, 2011
I am reading dates from a table in a database to display in a DataGridView column that is formatted as a date. The problem is that when the value is null in the database my program errors out because it cant convert the value to a date. How do you guys handle this? *Edit: If I set the value of my date variable to "Nothing" it displays as "1/1/0001" in my DataGridView, and I would like the cell to be empty for the null dates.
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Jan 24, 2011
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]....
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May 5, 2012
I use a dbDataAdapter to populate a DataTable from an unlinked oracle database.I have a dbDataAdapter that I want to insert rows into an SQL Server table using SQLCommandBuilder.I have been trying all day to update the DataTable that references the SQL Server table with the data from the Oracle DataTable so that I can insert the rows.
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Jan 29, 2008
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.
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Aug 27, 2009
I have an RDLC report that I am rendering directly to the Response Stream as PDF (rather than using the ReportViewer). In the code that renders the report, it's DataSource is bound to a List(Of ClassA) objects defined in a custom assembly. This seems to work for the most part. My problem is that I can't seem to handle the situation where a nested object is null. For example, given ClassA and ClassB (the nested object) defined as follows:
Public Class ClassA
Public Id As Integer
Public Name As String
[Code]....
the report displays "#Error" if TheNestedObject is null. If TheNestedObject is not null, it correctly displays the Name.
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Jan 11, 2012
Public Sub checkemail()
sqlcheckemail = "select Email from WEBUSER where Email='" + TBEmail.Text + "'"
Dim dscheckemail As New DataSet
[Code]....
if u see the one that i've commented is the one i already googled at tested...so now if the email address exist in the db..everything works wonderful..but if it doesn't exist the code should process the one that does not satisfy the first if statement...but now i'm getting the result as "There is something" eventhough the email does not exist in the db...
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Mar 1, 2010
I have the following code in my application. When it is executed it brings out a null value at times, where i am sure there should be a value returned. I have checked by running the sql statement in the database and it returns the correct value. What could be wrong with my code? [Code]
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Oct 15, 2010
I keep getting the error "Object reference not set to an instance of an Object" on the below highlighted line of code and I understand why. It's because I'm checking for something that hasn't even been initialized yet. My question is, what's the best way to check a DataTables row count without getting that error before refilling it?
If Not ds.Tables("tblNotes").Rows(0).IsNull(0) Then
ds.Tables("tblNotes").Rows.Clear()
End If
adp.Fill(ds, "tblNotes")
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May 12, 2011
I"m completely stumped. I've looked here[url]... Changed my connectionstring appropriately. My dataset is fills with data. The Excel file already exists, but has nothing but a Header row. I can't understand why the dataset can't push the values to Excel. The only thing it's doing is inserting a bunch of rows. There's nothing so far indicates something is wrong. [code]...
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Mar 29, 2011
[code]...
Dataset table not updating The reason why everything ends in 1, is because I have another instance running with similar names... so disregard that.
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Jul 16, 2010
Here's my code which is called on Form Load:
Public Sub PopulateSites()
Try
cn.Open()
Dim SQLCmd As New SqlCommand()[code].....
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Dec 20, 2010
I have a datagrid that I use to display data from a SQL 2000 table. I am trying to write back any changes the user makes to the datagrid data back to the original table but don't know the proper method to do this.
Here is the code that populates the datagrid:
Dim TheDatabase As System.Data.SqlClient.SqlConnection
Dim ConnectionString As String
Dim cmd3 As New SqlCommand
Dim Adp3 As New SqlDataAdapter
[Code]...
I could use some suggestions on how to code the write back command that will allow the user to change the data in the datagrid and have those changes be written back to my tAdjustment table.
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Jun 27, 2011
I am working on a program that uses an SQL database which in terms has a dataset .xsd which im using. I need to be able to update my dataset so it can reflect any changes made during run time. I am using the internal data binding that vb uses so I am not doing anything manually.
I fill a table adapter with information from the dataset and table with this snippet of code:
Me.biweeklyTableAdapter.Fill(Me.DDSPayRollDataSet.biweekly, biwk.valpay)
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Jan 20, 2012
I have a simple one-line dataset which exists on a form. I do not want to add additional lines or delete. I just want the user to be able to save if they need to. So I added the dataset, dragged the fields onto the form and deleted the unnecessary icons to have only a "save" icon. I also changed the property of the database to 'save if newer' but I am stumped as to why it is not saving. Every example I see looks so easy-peasy and when I do it, I get the following error:[code]The "save button" didn't have code when I dragged the bindingnavigator to my screen so I used the code in the video as a guide to structure mine and it should have worked. :/
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Jan 23, 2012
I have an Access Database in which I am trying to add a row through a dataset. I am able to add the record to the dataset but I can't write it to the live database.
Dim connectionString As String = _
"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:extraTEST.accdb;Persist Security Info=False;"
[Code].....
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Aug 26, 2011
I have a DataSet where I need to filter the collection where one of the date columns is not null.
How do you term this in LINQ?
This is what I have so far but there is a compiler error on the w.CompletedDate field in the Where clause.
Dim completed = From ins In InspectionDataset.Inspection.AsEnumerable _
Where (Function(w) w.CompletedDate IsNot Nothing) _
Order By ins.Field(Of DateTime)("UpdatedDate")
I have also tried it the below way but the compiler will not allow the DBNull comparison.
Dim completed = From ins In Inspection.AsEnumerable _
Where ins.Field(Of DateTime)("CompletedDate") <> DBNull.Value _
Order By ins.Field(Of DateTime)("UpdatedDate")
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Sep 7, 2009
I need to check if a value from a date column is equal to null. I can't find how to do it.
Wat I got now is:
if ds.tblBooking(row).CancelledOn.compareTo(dbnull.value) = true then
But this doesn't seem to work, I think it's because I'm using a strongly typed database.
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Nov 8, 2010
On a form i have several text boxes binded to a bindingsource and including a datagridviewI have populated the textboxes with database fields successfully and the datagridview displays the correct information.I have the following code to save the information to the database but i cannot get it to work. [code] I have tried many code examples here in order to save the data, none of which has worked.Can anyone please help me with this?
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Mar 11, 2010
I am having a problem updating an access database with new information from an updated dataset. the database consists of 4 columns: User_ID, Login_Name, Password, Access. The following code makes a connection to the database, fills a dataset with the data from the database, reads a txt file with user name and passwords, and should update the dataset and then the database. However, I keep getting an Syntax error on the INSERT INTO statement on the datest.Update(dsUser,"User") line. I have found multiple posts on here showing the correct syntax of how to update a database, but I can't seem to get it to work.
[Code]...
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Jun 12, 2011
so I was originally having problems even saving the data, but I can now get it to stay in the dataset, and when I switch to another page it stays there when I go back to it. Although when I close the form and reopen it, the changed data has not saved. I know that it is because I have only updated the dataset and not the database, so was hoping someone could give me pointers of how to approach it.
[Code]...
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