Using A Loop Condition To Check If There Is Null Value In The Columns?
Feb 15, 2010
I'm using a loop condition to check if there is null value in the columns, then remove it.
-Original author
[STart:]
For i As Integer = counter To dt1.Columns.Count - 1
For x As Integer = 0 To dt1.Rows.Count - 1
if some condition then
something = true
[Code]...
Sometimes it runs correctly and sometimes even though when i becomes greater than (dt.columns.count - 1), it still executes the for loop and throws an error that there is no column with that index. I must be missing something here but I'm not able to debug the issue.
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Mar 14, 2011
Makes the following statement about the code below:
**"The computer evaluates the loop condition in the Do...Loop statment to determine whether the loop instructions should be processed. In this case, the inputsales <> String.Empty condition compares the contenst of the input sales variable to the String.Empty value. As you know the String.Empty value represents a zero length, or empty, string if the inputsales variable is empty, the loop condition evaluates to True and the computer process the loop instructions. *If on the other hand the inputsales variable is not empty, the loop condition evaluates to false and the computer skips over the loop instructions.
Based on the code I think it is the opposite: ...that while the inputsales value is not empty it should evaluate to true and process the loop and if it is empty it should evaluate to false and skip the loop?
See below.
Option Explicit On
Option Strict On
Imports System.Globalization
[CODE]...
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Jun 4, 2011
How to check a check box based on a condition at run time?
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Jun 22, 2011
How to update columns in datatable using linq without conditions. I have an idea that I'm just gonna loop all the data in the datatable but don't know what comes in LINQ.
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Feb 27, 2012
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.
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Jun 20, 2010
What is the correct syntax to go to the next sequence in a loop if certain conditions are met bypassing the contents.
I am using goto and inserting a line number which is probably not the best way.
I.E. My syntax:
For i = 0 to 100
If i = myvariable goto 100
Functions to be performed
[Code]....
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Jul 20, 2011
So I have a few variables in an array a I want to compare another variable to each of them, if it is the same do something, AND STOP THE FOR LOOP. else carry on the for loop. So...
for i = 0 to 4
if variable = a(i) then
do some stuff
[code]....
how do i end the for loop from within an if statement that is in the for loop
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Jul 15, 2011
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]....
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Oct 28, 2011
I have a list of string in an array. I'm loop through those strings and if the text of a combo box matches one of those strings, I want a message to appear. If they don't match, I want a method to be executed.
[CODE...]
The messagebox appears, but the method is still executed. Which means it isn't stopping when it finds the match. I tried exiting the loop, but it still doesn't work.
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Mar 25, 2009
My application uses 12 checkboxes. Dependant on the status (checked or unchecked) different action are required. I can't seem to be able to structure a for next loop to do this.
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Mar 23, 2010
I have a for loop condition as below coding for looping to change word on label.text, but as a result, it just only display the last value.
how can I do to display each value for a looping.
i want the result is the label1.text to show 1 then 2, then 3, then 4.......finally is 10.
for i as integer = 0 to 10
label1.text = i
next
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Jan 16, 2012
I have a button and i want it to check for a condition to display different msgbox.
Below is my code:
Dim a As String = "";
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
[Code].....
But i got the following error when i clicked on the button.
"Input string was not in a correct format. "
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Jan 19, 2010
In my program, I have a condition I need to constantly check for. When my program gives an error, I change a label to a different text, lets say "fail" for now. I'm trying to make a condition where the program constantly checks for the label change to "fail" from the start of the program. I am having trouble trying to get this to work.
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Dec 1, 2011
i'm starting to learn VB, i've wrote a few little programs following the books and internet resources, so far so good until now, i have to check a range of double integers(e.g. 170-50) if the left integer is == 170 and the right integer is == to 50 then you profit.i have to do this about 200 times but i just need a litow to get started, i've searched for about 4 hrs and read for about 5 and still nothing.
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Jun 21, 2009
I share my internet connection with other users through LAN. There's some one who keeps cutting me off from time to time to increase his download speed.I know that there is some orders that can be written in the command line to reconnect to the internet after every cut but I don't know them.I started teaching myself programming under VB 2008 Express as a hobby few weeks ago. I was wondering if there is a way to write a program in VB to check the connection condition every few milliseconds and reconnect again to the real gateway till the attacker get bored.
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Sep 27, 2009
Reading Excel in .NET - some columns are read in as null
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Jan 20, 2011
Why below code has error in VB.net 2008?Dim Object1 As New Class1Object1.SetId = If(rbSet.Checked = True, Convert.ToInt32(txtSetId.Text.Trim()), DBNull.Value)What I'm trying is to set a property of an object by a condition.
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Oct 22, 2009
TableAdapter.Update(...) Inserts NULL Values in all columns for a new record?
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Feb 2, 2011
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?
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Jun 24, 2010
I have some code which gets child items for a menu via the GetChildren function which takes a list of menuData: Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
If menuData.Children IsNot Nothing Then
menuData.Children.AddRange(GetChildren(menuData))
End If
Next
If I check if menudata.children isnot nothing, it always is nothing because the GetChildren function is yet to run (providing the child items, which do exist). If I remove this check and just have this code:
Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
menuData.Children.AddRange(GetChildren(menuData))
Next
Then I am presented with a Object reference not set to an instance of an object error on menuData.Children.AddRange(GetChildren(menuData))
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Apr 7, 2011
All I want to do is check if an object is null, but no matter what I do, if it compiles, it throws a NullReferenceException just trying to check! Here's what I've done:
[Code]...
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Apr 8, 2011
I have a dataset. I'd like to check if one item in the dataset is null or zero.
If IsDBNull(ds.Tables(0).Rows(0)("TotalCostPerUnit")) or CInt(ds.Tables(0).Rows(0)("TotalCostPerUnit") = 0 Then
Exit Sub
end if
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Sep 30, 2009
Dim Conn As ADODB.Connection
Dim Null As String
Dim NullRecordset As ADODB.Recordset
[code]....
Im trying to check my database for a null value. If the database is null, then I want it to start the timer, otherwise I want it to skip over some stuff and automatically load the main form.
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Oct 27, 2011
I am trying to check to see if a DataSet is null or not. If it is I would like to show a MessageBox. For some reason it is not recognizing null returns and skipping the message box and going right to the Else commands. [code]....
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Aug 13, 2010
I have a problem with verifying db null value. Actually I don't know the syntax.
Here is the code.
If Not IsDBNull(Me.DeliveryReviewDataSet.Delivery(Me.CustomerIDListBox.SelectedIndex).Signature) Then
"Signature" is the image field (binary data).
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Jun 29, 2010
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If MyBase.Dispose(disposing) <> DBNull.Value Then
Dispose() = DBNull.Value
[Code]....
I am getting error
1) Expression does not produce a value.
2)Expression is a value and therefore cannot be the target of an assignment.
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Sep 21, 2009
I retrieve data from database like below. How do I check whether the value retrieved from database is null?
[Code]...
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Jun 29, 2010
I have the following code:
Dim i As Integer
For i = 1 To 20
Dim captionTextBox As TextBox = DirectCast(Me.FindControl("news_Image" +
[Code].....
Where the comment is in the code above, I need to insert the value of the textbox (text) into Linq columns. For example: articleToUpdate.news_Image1Caption, news_Image2Caption, but I need to change the number after news_ to the value of i in the for loop.
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Feb 8, 2010
I need to loop through my datagridview1 to obtain the name of each of the columns to set the attributes. I'm not sure what I need to look for when doing this.
I tried:
For Each Field As String In DataGridView1.DataGridViewColumn and For Each Field As String In DataGridView1.Columns But it's giving me errors. What would be the proper way to loop through the DatGridView and get the name of each column?
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Mar 11, 2012
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 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
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