I'm querying a SQL DB and sometimes the result is Null, so I thought I would test this but my code results in an error "Data is Null. This method or property cannot be called on Null values."
Here is a snipet of my code:
For i = 5 To 6
cmd = New MySqlCommand(query2t & i, db)
rdr = cmd.ExecuteReader()
rdr.Read()
If Not IsDBNull(rdr.GetUInt32(0)) Then
[Code] ......
I have a fairly simple piece of code:
Private _PurchaseDelivery as PurchaseDelivery
Protected Overrides Sub InsertItem(ByVal index As Integer, ByVal item As PurchaseDeliveryItem)
[Code]....
Which is inside a class which overrides a custom list base. The code is occassionaly throwing an unhandled exception, System.NullReferenceException, on this line when used in production:
If _PurchaseDelivery IsNot Nothing AndAlso _PurchaseDelivery.DefaultSKUBinID.HasValue Then
DeafultSKUBinID is declared as an Integer? (Nullable Int) in the PurchaseDelivery class. I cannot see what might be causing this error, why would this be returning an error?
checking im my textbox contains null valuefor example i have ten textbox how do i know if a textbox has no text in it?then gotfocus to that specific textbox?
View 3 RepliesI'm using Visual Basic .NET to work with a USB HID device.Most of the time, I can receive data from it perfectly... but one out of every thousand transfers or so, my code will think it has received data when it actually hasn't.The device writes to an array of bytes. I wanted to check to see if the received packet is empty, by doing something like this:
If myDevice.dataPacket(1) <> Nothing then
myDevice.rxDataReady = False
[code].....
ve a simple vb code similar to the below,
Function getvalue (ByVal Val as double) As string
Dim Num as Integer
Dim Prd as double
[code].....
Is there anyway to check for a null here before it reaches this part of the code? tmpLabelData(0) = m_node.Item("CONTAINER_NAME").InnerText. Some XML has it while others do not. I cant seem to find a nice way to handle a null on these?
View 1 RepliesI have some code that is meant to check the length of the values in the text boxes, and if any of the boxes has no content the length of the string is 0 (or null). Here is the code:
If (Len(Form_MainScreen.Ctl48.Value) Or Len(Form_MainScreen.Ctl49.Value) Or _
Len(Form_MainScreen.Ctl50.Value) Or Len(Form_MainScreen.Ctl51.Value) Or _
[code]....
When one string is blank, the length check becomes "null" and so does the whole statement.But if the length checks are all not null, the if statement becomes a "1" and then procedes to execute the Do X procedure again.
I 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 ?
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")
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 RepliesI am trying to write a generic function that will check each database parameter to see if it is null, and if so, return DBNull; if not, return the object.So here is my function:
Public Shared Function CheckForNull(ByVal obj As Object) As Object
If obj <> Nothing Then Return obj Else Return DBNull.Value
End Function
[code].....
I constantly find myself having to do code similar to the following.[code]Is there anyway to check for both on a single line? When i'm checking a condition for a great number of answers, I sometimes end up with conditionals 6-sets deep. If i check for null first, an error still pops up, even though VB shouldn't check since the first condition failed. i.e.[code]
View 8 Replieshow to check null excel worksheet?
View 2 RepliesI have a DataGridView1 populated by sql searches. On the rare occasion that nothing is returned, my app cannot make use of data so I'm trying to check for null values. My code below is not correct because IsDBNull is not a member of the of the DataGridView1.
If DataGridView1.SelectedRows(0).IsDBNull Then
MsgBox("Nothing to display")
Exit Sub
End If
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.
I'm implementing a State Machine in WF 4.0. In some transitions, I have added a condition where I check that some variables have the expected values. The variables are enums and booleans, and everything is fine.
However, now I tried to evaluate when a property is null. I have and argument in my workflow, let's say, 'MyArgument'. In a transition, I try to put a condition like 'MyArgument.MyProperty = Nothing'. I never developed in VB.NET, I don't know if I'm missing something here...
VS2010 gives the following error: "Error 4 Compiler error(s) encountered processing expression "MyArg.MyProp = Nothing".
Operator '=' is not defined for types 'XXXX' and 'XXXX'
The type names are exactly the same, and I have debugged VS2010 to ensure that my assembly is not loaded from 2 different locations.
How can I check if the property is null or not?
BTW, I'm using VS2010 SP 1, with .NET Platform Update 1 installed, on W7 64 bits.
I am trying to implement a function for my SSRS report which will return a color value depending on the values of three dates.
[Code]...
I am using following code in rowdatabound fn.
Protected Sub gvwMileStone_RowDataBound(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs)
[code]...
ddlEProjectLevels is dropdownlist in edititemtemplate.Whwn i click edit in 1st row ddlEProjectLevels gets loaded with data from database.But in 2nd row dropdownlist does not contain values.Again in 3rd it gets loaded from db.Means in alternate rows,when i click edit dropdownlist(ddlEProjectLevels) doesnot load values.Can anybody help?
The following piece of code executes a SELECT query and places the result into a textbox, but if the query returns nothing an error appears saying that there is no value and it won't continue the lines of code after it. (I modified code I found on a website after a Google search, I'm not sure if this is the best way to do it but it seems to do what I want.. so far)
[code]...
How would I change the code so that it checks the query to see if it returns a result? I'm still not too sure what the SqlDataReader can do fully, so I'm not sure if it can check for a result.
This seems like a pedestrian problem, but I just can't seem to find a solution. My problem is that I can't seem to find a way to search my datasourcefor a null value. Here's a simplified version of the problem: suppose we have a form with 3 textboxes and we wish to find a record on our datasource. if fields 1 and 2 have a value and field 3 is null, then how can I make a query using .net that searches for the values of the first 2 fields and a null value for the 3rd field? For example, suppose field 1 has a value of "ABC" and field 2 has a value of "DEF" and field 3 has a null value Now, how can I construct a query that searches "ABC" for field 1, "DEF" for field 2, and null for field 3?I'm using sqlce and below are some examples of what I've tried so far:
Dim Fld1 As New SqlServerCe.SqlCeParameter, Fld2 As New SqlServerCe.SqlCeParameter, Fld3 As New SqlServerCe.SqlCeParameter
Fld1.SqlDbType = SqlDbType.NVarChar:Fld2.SqlDbType = SqlDbType.NVarChar:Fld3.SqlDbType =
[code].....
Table relationship[code]...
There are some TimeSheet that have no TimeRecord, which I need to select as well. How can I select all of them to make selection like above wanted result? I'm thinking of how I can include some condtion checking in the query to see if this TimeSheet has no TimeRecord then no need to Sum(tr.BonusHour) just assign TotalHour to zero.
I have a sql query which is returning null value below is the section the iID is null.Once debugger reaches this it goes to exception as its result is NULL. How to control debugger from going to the exception.
[Code]...
From r In ReceiptLines
Where
r.RECEIPT.RECEIPTDATE >= _reportStartDate
And r.RECEIPT.RECEIPTDATE <= _reportEndDate
[Code].....
I am fetching all departments and their sales, average, count from the ReceiptLine, Receipt, ReceiptDiscount tables. The problem i am facing is, if i remove where discount > 0, I am getting null exception. But if I include that, then I only get sales that has discount. How would I write query that bring all sales less discount (if it has one).
I have a select statement which was returning the required values but when I changed the OS date from English(US) to English(UK), it now returns null. I believe the problem is concerned with date since in the query am selecting values where the date from the database is the same as the date in a combobox but I don't know what else I can do. It almost looks like the dates in the combox and in the database are not the same and yet the date in the combobox is actually retrieved from the database and has been returning values fine until I changed the system date format.Here's my select command:
cmd4.CommandText = _
"SELECT sum(brought_qtty), recieved_qtty from brought_coffee, centre_weigh where brought_date=#" & _
dtComb.Text.Trim & "#" & _[code].......
I'd like to take all suggestion either in C# or VB.NET.I have a DB diagram like the image below. I also include the database script here [URL]In the Students table, CountryId and RoomId column are allowed null. Because some records do not have info about room and country yet.Also, some students do not have essays.I'm doing a joint query with all tables. I want to select all students to project the result like this:Wanted query result.
Here's my current query that gives the result like the image below:
Dim db As New DBDataContext
Dim query = From st In db.Students _
Join c In db.Countries On c.Id Equals st.Id _
Join r In db.Rooms On r.Id Equals st.RoomId _
[code].....
current query result I got only one result back because I have (2) William NoMan record in every table. But I don't get anything about others, like (3) Sync Master who has everything but RoomId.What do I need to modify the query above so it will give me all students like in the wanted query image above?
I m trying to filter a sql db with many filter criteria which inert the user in textboxes .. i ve tryed this query
[Code]...
've got a function that takes two parameters (a delegate and an integer) and then creates a LINQ MethodCallExpression, which it uses to gets the results:
Public Delegate Function CompareTwoIntegerFunction(ByVal i1 As Integer, ByVal i2 As Integer) As Boolean
Public Function Test(ByVal pFunc As CompareTwoIntegerFunction, ByVal i1 As Integer, ByVal
[code].....
Is there any better performance by checking for a true value like this:
[CODE]..............
Than like this:
[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]....