Encounter Occurs When Return NULL Value To The Textbox?
Mar 29, 2009
i am retrieving data using data reader. Whenever a null value fetches from the column, the compiler encountering an error. The error occurs when column value contains NULL. I am using Visual Basic 2005.
Please look at the following error which is in red color:
DEVNA11.Checked = IIf(IsDBNull(dr("dev_serv_desc_final_na")), 0, dr("dev_serv_desc_final_na"))
txtPlanServDesFinal.Text = IIf(IsDate(dr("dev_serv_desc_final_planned")), Format(dr("dev_serv_desc_final_planned"), "dd/MM/yyy"), dr("dev_serv_desc_final_planned"))
System.ArgumentException: Argument 'Expression' is not a valid value.
I am currently using a sql data reader (in vb.net) to extract an article object via a stored proc from a SQL Server 2008 database. Part of this object includes the two properties shown below:
My problem is that the Truthfulness and Relevance may return a null value and this is causing the function to fall over.I think I understand why. I am asking for an integer value (getin32) and because null is returned it fails.How do I accommodate the null value from the database so it does not fall over?
I'm having trouble figuring out what to do with the bolded part, when there are no nodes to return.If there are no image tags inside the <images> tag, i get an "Object reference is not set to an instance of an object".I have been searching and searching for an answer but can't find one.
Dim orders = From o In xmlLinq.Descendants("order") Select New With { _ .orderID = o.Attribute("id").Value, _
Take the below example. I would expect the IsInterned method to return null, because this string can't possibly be in the intern pool having started up the test app for the first time? I would also expect, that if I did something like string.intern("this112233StringCan'tPossiblyBeInTheInternPool!£$%") first, then this would legitimately be returned by IsInterned from the pool. I've also done the same in c# and the behaviour is the same.
Whenever I use strings in code, I tend to do something like textbox.text = string.intern("someValue") etc or if (textbox.text = "someValue") etc. Infact, whever strings are being used, I've gotten in to the habbit of using string.intern. Is this a bad habbit rather than using constants or the resources file?
I want to retrieve total value from sales table in sqlcommand object. Below is my sample code.I will get error if there was no data in the tabel that matched my query saying that null could not be converted into decimal.
I would not get error if there was data that matched my query and returned the total value in tmpSales variable.My question is what is the best way to deal with this situation?
Dim CmdTmp As System.Data.SqlClient.SqlCommand
Dim tmpSales As Decimal
CmdSales = New System.Data.SqlClient.SqlCommand("SELECT SUM(Total) FROM Sales WHERE Date>= '1 Jan 2011' And Date<= '30 Jan 2011", ConDB)tmpSales = CmdSales.ExecuteScalar
How can i return null values in if statement above. This statement is not working if condtion is false its retruning me 0 value even if condition is false
dim d as nullable(0f Decimal) d=(if(_dr("value") isnot dbnull.value,Convert.toDecimal((_dr("value")),Nothing)
I have a datetimepicker and combobox on my form. If a user does not change the date on dtpicker or does not change text on combo box, these controls return null value, and the save operation fails. The controls are bound to data in a database.
How can I get how many times a string occurs in a textbox? I thought the find function would return the number of times found but it seems to return the location of it.
[if me.textbox1.text= system.dbnull then msgbox("please inter a value")] it says system.dbnull can't be used as an expression so how can i check the if the textbox has a null value
What i want to do is to read a value either null or not null from my oracle database using DataReader and store in a textbox. But i have an error.InvalidOperationExcepionHow can i avoid this error.Or is it possible to catch the exception to ignore null values read by the datareader?If the option is to catch the exception how may i do it?
Dim Dr1 As OleDb.OleDbDataReader = Cmd3.ExecuteReader Dr1.Read() lect_name = Dr1.GetValue(1).ToString
I have a couple of textboxes whose databinding's text is set and also readonly is true and visible is false. but when I try to read their values they are all null unless I turn their visibilty to true. The same method is also needed to add a new row to the table (when using bindingsource1.addnew()).
Im sure this is a very simple and easy to answer question but I've been looking at this too long and being new to ASP I cant seem to find a solution that works.
I have an ASP calendar extender, I click it and the calendar displays as expected, the selected date appears in the textbox, but when the page then posts back I cant get the selected date value from either the textbox.text or the calendarextender.selecteddate properties, I tested this by trying to assign these values to a string variable in the page_load event.
I have a form that has several controls, most of them are textboxs. All controls are binded to a bindingsource. The controls that always have values, they are displayed correctly, but the others ones that have null values in the data source, the default null value doesn't show up. This problem it's driving me crazy... There must be something that i'm missing. Some of the code that i had used with no luck:
so im using the Imports System.Math to help implement trig functions//what im trying to do is import the value from the textbox into the function and return the value. [code]
I am having an issue doing the following:I would like to be able to count how many carriage return there is in a textbox.Is there a function that already exists that could search in the textbox the amount of carriage return ?
Where Me.Note is a string that I am looking for and replacing it with the contents of txtNote.text. And then storing it all back in the string CoverPage.CoverPage is an rtf string that will holds place holders for the text I want to change.(That works) But when i update the note that may have a carriage return in it, the coverpage does not reconize the carriage returns comping from the Multiline textbox when its displayed.I have tried replaceing Enivronment.Newline with vbCr, vbCrl and whatever else I can think of. is there an issue with taking a string carriage control and tranfering it to a rtf carriage control?
Currently I have a gridview bound to a datatable which is populated with groups from the AD. I need to be able to add search functionality so users can type in part of a group name and have the results display only groups that fit their search criteria.
I have a textbox that get the date from the system itself, is working good and I have another textbox that will get the date that the person needs to bring the Book back. I wont the person to type the date but the program do it automatically (something like 20/04/2009 + four days=24/04/2009) automatically, something like if the person took the book on todaydate(20/04/2009) the function add more 3 days and display on textboxreturn( 24/04/2009). I don't want the person to type the return date, but to build a function that do it.... 0&1Bytes
I have to count the amount of enter (carriage return) someone did in a textbox set as multiline. Is there a function already there or one that I can create that will count how many times someone did hit enter.
I've created a basic search form. I have a textbox with a search button and an Access Database as the backend. I have also added it as a new datasource. What I'm looking to do is grab the search string from one textbox and return the data to another textboxt. I have a table called "VehicleInfo" and I want to search the field in my table called "VehicleID" and return the vehicleID I searched for into another textbox. I'm really new to VB. I understand databases and basic code structure, I just don't have a good grasp yet on how these two work together.
Public Class frmMain Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'TODO: This line of code loads data into the 'Garage_ServiceDataSet.Service' table. You can move, or remove it, as needed. Me.ServiceTableAdapter.Fill(Me.Garage_ServiceDataSet.Service) [Code] .....
