Have A Field In A Datatable (dt) That Can Be Integer Or NULL?
Mar 1, 2010I have a field in a datatable (dt) that can be integer or NULL.
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Check 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 RepliesLoop Datatable And Select Checkboxlist Item Based On The Datatable Field Values
Aug 18, 2011I am trying to display value of the field ("UserID") for every row exists in datatable to checkboxlist(make the checkboxlist item selected).
I used for loop, but only the field value from last row of RoleUsers table is selected in the checkboxlist.
Here is my code
Private Sub DisplayRoleUser()
Dim conn As SqlConnection
Dim cmd As SqlCommand
[Code].....
Make An Integer Null?
Sep 2, 2010I have an update function that updates an sql server db table through a dataset. One of the fields in the table is an integer and accepts null values. So when I am populating the update function I need a way to enter a null in when the function wants an integer.
I tried to do it this way but _intDLocation = "" throws an exception
[code]...
Passing In NULL Integer?
Feb 8, 2011I have a function that takes in a number of parameters.. it then does a db insert.i have a foreign key on one of the fields (modelID)i want to pass a NULL if no model ID is selected.[code]but now i get an error saying: Nullable object must have a value.if i pass in a 0, it does not insert because it breaks the DB constraints.
View 4 Replies[2008] Check Integer For Null Value Instead Of 0
Jan 19, 2009Basically, when you set an Integer to "Nothing" it seems to equal the same value as if you were to set it to 0. So, in a function that returns an Integer how can I return something that will show that the function failed? In most cases I would use -1 or something but in this case I need to allow for negative values too.
Here's some more detailed information: I'm using the GetValue method of the Microsoft.Win32.RegistryKey class to read a numeric value from the registry. The GetValue method has an optional argument that you can pass in that specifies what should be returned if the value did not exist, normally I would use Nothing but in this case because I am storing the returned value in an Integer then it is just the same as if the GetValue method returned 0 (which is a valid value in this case).
Example:
vb.net
Dim Reg As Microsoft.Win32.RegistryKey = My.Computer.Registry.LocalMachine
Dim SubKey As Microsoft.Win32.RegistryKey = Reg.OpenSubKey("SYSTEMCurrentControlSetControlTimeZoneInformation", False)
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Error When Field Is NULL
May 2, 2010I using ADO to get som values from a SQL DB one off the fields can have the value NULL And if i use:
txtinfo.Text = RS(
"info").value
Then i get an error.I have try with IS NULL - but that dosn't work
Remove Row In CSV Where Field In Row Is Null?
Nov 1, 2010how to delete row in a CSV file where there is a null value in a partcular column? I am using VB. There are three columns I am using Post Date, Account Number, and Credit Amount. I want to delete all rows with null values in the Account Number column. I am very new to VB, took one class. I am using the Microsoft.VisualBasic.FileIO.TextFieldParser?
View 1 RepliesSet Date Field To Null Value?
Dec 12, 2011I am using visual studio 2010. I have a text box bound to a sql datetime field.I have to be able to either set or clear the text box. I can set it to any date fine, but when I try to clear it I am unable to save the record.i am using the binding navigator to save.
View 5 RepliesAssign A Value To Nullable Integer Via A Ternary Operator / It Can't Become Null
Apr 19, 2012If you assign a value to a nullable integer via a ternary operator, it can't become null..While this question may seem like a duplicate of many, it is actually being asked for a specific reason.Take this code, for example: Dim n As Integer? = If(True, Nothing, 1) In that code, the ternary expression should be returning Nothing, but it's setting n to 0. If this were C#, I could say default(int?) and it would work perfectly. Now it looks like I am going to have to ditch the ternary and use a regular If block, but I really want to use the ternary. If Nothing were truly VB.NET's equivalent to C#'s default, how can you explain this behavior?
View 1 RepliesNull Reference Exception While Trying To Initialise An Integer Array?
May 15, 2011I am getting System.NullReferenceException:Object reference not set to an instance of an objectwhile executing the below code..!!
Dim arr() As Integer
Dim g,j As Integer
g=10
[code]....
Test For Null Value Of A Field In An ADO Recordset?
Oct 24, 2010Question is: How to test for null value of a field in an ADO recordset.Using Visual Studio 2010 Ultimate - VB.NET
ADO Connection to ODBC database
I am working with a table that contains about 10,000 records of which I need to do additional processing on about 1500. The records I need to process are qualified by the field'Cataloged' = True. The problem I have is the table allows for True, False or Null values (I have no direct control of the table to change from allowing Null) for the field I need to test.I run into errors when the value of the field is Null and need to figure out how to determine its Null state prior to trying to qualify the field as True or False value to prevent the errors.
.net - Checking For Null In Date Field?
Oct 25, 2011I have an ASP.NET application that crashes when a null date value is returned.
The code line is:
excelWorksheet.Cells("A" & xlRowCounter).Value = IIf(IsDBNull(dRow("sysdate")), "", Format(dRow("sysdate"), "MM/dd/yyyy"))
Error message:
ERROR: System.ArgumentException: Argument 'Expression' is not a valid value.
How would I check for a null date, and replace it with "" in my app ?
Dealing With A Null In A Varbinary Field
Aug 3, 2009I'm trying to test a varbinary(max) field to see if it's null. I'm trying to figure out if it's a null or not in the select statement, hoping to avoid having to do this locally for every row of the returned dataset. This is the SQL I'm using,
[Code]....
Display Null Value From SQL Image Field?
Dec 30, 2009I use following codes to display image from sql server. [code]...
View 3 RepliesInsert Null Value In Date Field?
Nov 22, 2010i have a maskedtextbox which will accept only date in the format of "DD-MM-yyyy" no i want to insert this date in my db. i have done this successfully.
Now i want to insert null value in through that maskedtextbox .
Setting First Field In A Combo Box To Null?
Oct 1, 2011I have a databound ComboBox on my form. Is there any way that I can make the first field blank.
I can do this with a DropDownList in the HTML part of .Net but is there a way to do it for a ComboBox?
SQL Record Search But Field Is Sometimes NULL?
Mar 2, 2010I am trying to do a SQL query to see if an Address already exists in my database. My addresses are structure like this:
line1
line2
line3
city
state
zipcode
country
Sometimes line2 and line3 are NULL values in my database.I am using .NET TableAdapter and DataTable to make my query. When I try to pass in my line2 parameter (@line2) it is equal to a string with value = nothing. My database does not interpret this as NULL and says the records don't match, but I know they do? How do I pass in a string = nothing and have it compare to a NULL value in the database as being equal? I have tried string = DBNULL.value but won't compile.I have done similar comparisons with integers etc. using integer = Nullable (of integer) but this does not exist for strings.
VS 2008 Put Null Value In A Field Number
May 15, 2009I have in my DB a few number fields, but I would like put null values or empty values in some of this fields...
I had try this but without results:
If valorcolocardebito = 0 Then
valorcolocardebito = Nothing
End If
[Code].....
How To Check If A Datatable Is Null Or Nothing .net
Apr 26, 2012How can I check if a datatable has never been set ? or Null or Nothing ? I don't mean empty Datatable ... For example,
[Code]...
Getting Null Value Of Hidden Field At Server-side
Feb 18, 2011I am calling a Java-script function, in that i am passing the value of hidden field, that hidden field i want to use at server-side, but the value of hidden field is null.[code]...
View 1 RepliesInsert Null Value From A Textbox At Numeric Field?
May 17, 2012Why when I try to save a null value from textbox at sql server 0 is saved?
View 2 RepliesMade Empty Or Null Field In Datagridview
Nov 15, 2009I key-in data from textbox to datagridvie..........the date data the format datatable is:
[Code]...
Select All Records Where A Field Is Null Using LINQ?
Jan 25, 2012I've got a table that caches calculated values for certain dates. I want to use LINQ to select all rows where the calculated value fields are null.But when I use isNothing I get an error that LINQ can't translate this into T-SQL. Is there a way to select null values with link, like this...?
Dim var = From rec As Record In myDataContext.Records Where IsNothing(rec.calculatedValue) Select rec
Other posts on stackoverflow mostly discuss how to avoid or check for null values with LINQ.
Note: I can't just set cacluatedValue's default to -1 to flag records whose calculated value has not been set (and then select those records) because I run queries that sum/average the calculated values. Selecting nulls seems cleaner and less bug-prone.
Setting Date Field To Null With DataTables?
Mar 31, 2010Im writing an app which connects to a SQL Server database, via datasources / datatable.When Im looking at my .xsd I can see DataTables containing DataColumns. Each DataColumn has a 'NullValue' property which defaults to '(Throw exception)'.Because I have nulls in my tables I have gone through the fields and set all System.String fields to NullValue = 'Empty', System.int32 field to NullValue = 0.
View 1 RepliesVB Expression For Finding Null Value In DataRow Field
Jan 29, 2010I require the expression which determines if a Data Item in a DataRow is null.
Required Code
If MyDataSet.Tables("MyTable")Rows("MyRow").Item("CheckingItem") [IS NULL] Then
'[Do Something]
End If
Attempted Code Resulting in Thrown Exceptions
I have attempted the following code which resulted in the exceptions posted under them.
If CType(ds.Tables("MyTable").Rows(0).Item(2),System.String) = "" Then
Me.lblOutput.Text = "Good"
End If
System.InvalidCastException: Conversion from type 'DBNull' to type 'String' is not valid.
How To Generate CheckBox Field According To Integer Value In Database
May 9, 2012I want to generate checkbox field using GridView and system will calculate how many field to display according to number of totalDay. If totalDay stored in database is 7, so upon calling the eventID it will generate 7 checkboxes, D1-D7 checkboxes field will appear; if totalDay is 5, it will generate 5 checkboxes, D1-D5 checkboxes field will appear.
In PHP, I manage to auto generate number of D field I want according to value totalDay. But I do not know how to code in VB. The PC Fair Event has duration 7 days, so it will display 7 checkboxes after user select event and booth to book: The Carnival 2012 has duration 5 days, so it will display 5 checkboxes after user select event and booth to book:
The code in PHP which can generate the checkbox:
$query = "select * from booths, eventinfo where booths.eventID=eventinfo.eventID && booths.eventID = ".$id."";
$_SESSION['EVENT_ID']=$id;
$result = mysql_query($query);
$result2= mysql_query($query);
[Code] .....
Cannot Leave Field Null When Running Insert Statement
Jun 8, 2009I have the following query that I use to create a new record in a database. If I leave any field on the form blank, for example, it throws the error "Memo.Lastname" cannot be a zero length string. Other than that the query executes appropriately.
Private Sub cmdSaveMemo_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles cmdSaveMemo.Click
If Len(Me.txtMemoID.Text) <> 0 Then
Memo.SaveMemo
[Code] .....
DataRow Not Produced Via DataAdapter.Fill If A Field Is Null?
Apr 20, 2012I there a way to set up my DataTable so a field (or all fields can allow nulls if you can't set just 1 field) so oIDbDataAdapter.Fill won't leave out DataRows where a field contains a null value?
Dim oSqlCommand As SqlClient.SqlCommand
Dim oIDbDataAdapter As System.Data.IDbDataAdapter
oSqlCommand = New System.Data.SqlClient.SqlCommand( _
[Code]....
DateTimePicker Bound To Nullable DateTime Field But No Null?
Apr 7, 2010I have a date time picker bould to a Nullable Datetime field in a sql server datatable. The ShowCheckBox option is set to true. If the user unchecks the checkbox on the datetimepicker I would like to the field to be set back to null in the DataTable. The default behaveour does not seem to do this and there is no specific event for the uncheck.
Private Sub dtpCertDate_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles dtpCertDate.ValueChanged
If dtpCertDate.Focused Then
[code].....