Ado.net - Checking If Dataset Is Empty
Apr 2, 2011How do i check if the dataset is empty? I wrote the following code:
[Code]...
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VS 2010 Checking For Empty Field
Sep 1, 2011I have a field that I want to check to see if it has a value or not. But my code is not working. I am using:[code]
View 9 Replies[2005] Checking If A CheckedListBox Is Empty
Feb 20, 2009In my application I load a CheckedListBox from text file apart from looking at the form, how can I trap the error of not completing the action?
View 1 RepliesChecking If The Dynamic Text Boxes Is Empty?
Aug 5, 2011How will I check that the dynamic textboxes is empty;
Here's the code:
Imports System.Data
Imports System.Data.SqlClient
Public Class FunctionProcessor
Dim objcmd As New SqlCommand
[code]....
Nested If Loops Checking For Null And Empty
May 27, 2010I 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 RepliesVS 2010 : Checking For Empty Text Boxes Before Doing Calculations?
Sep 19, 2010I'm writing a program for my class, which pretty much is an energy cost calculator. It takes 4 inputs from 4 text boxes and multiplies them, and the result is the cost. Well, now I have to come up with a way to check for empty text boxes and display a prompt to enter a number. I've tried inserting multiple codes to display a prompt and to no avail nothing has worked, I also receive the error "when casting from a number, the value must be a number less than infinity" error.
View 3 RepliesChecking If Dynamic Text Boxes Are Empty/ No Input When Saving?
Aug 8, 2011For example, I clicked the Add Text box button, so it added 3 text boxes in the form (I used Dynamic text box so it can add multiple text box). When I input data to one of those 3 text boxes and then Save button has been clicked. It should checked whether the dynamic text boxes are empty or not. If there are empty text boxes, then saving data to db should not be continued and display a message telling the user that empty field(s) are invalid.
In the code below, it saves the data even if there are empty text boxes and I think because it is in the for loop, it checks the text boxes one by one and repeatedly displays the message box that I coded.
Here's the complete code:
Imports System.Data
Imports System.Data.SqlClient
Public Class Form3
[Code]....
Check Empty Dataset
Oct 4, 2011i have a dataset that takes results from a select to a sql database. the select returns rows and sometimes returns no rows. how can i check if the dataset has no rows from the select? [Code]
View 4 RepliesDataset Showing As Empty?
Mar 10, 2011Public Class ReceiptEntry
View 4 RepliesTell If A DataSet Or DataRow Is Empty?
Feb 23, 2012After much convincing by other people, I have finally started trying to use ADO.NET instead of ADODB. Unfortunately, my lack of knowledge regarding these objects has left me broken in one area. I tried converting the area where I am checking for duplicate records to use ADO.NET by checking if a student filling out a form enters the same first name, last name, and program or major as another record in the database as per my instructions. Unfortunately, in the following code snippet, it is not behaving how I thought it should and I am unable to diagnose exactly where the problem might be just yet.
Here is the code in question:
Try
Dim orion As New SqlConnection(strConn)
Dim sqlCmd As System.Data.SqlClient.SqlCommand = New System.Data.SqlClient.SqlCommand(query, orion)
[Code]...
I probably should have mentioned also that it never flags an error despite there being 'duplicate' records in the database at this point.
Checking Array Against Dataset?
Feb 1, 2011I am stuck with the following code (below). Basically, I have two data sources; a flat text file and a dataset. I am trying to put the primary key from the flat file into a simple variable, and the PK from the dataset into an array. I then use a 'for each' statement to compare the PK from the text file to the PK in the array (from the dataset). If they match, the "isValid" variable is supposed to equal 'false'.
Unfortunately, this is not working. the isValid is always true, which I know is not the case, and then I get a SQL error warning of primary key violation. I'm a bit tired, and not seeing it. Here's the code;
For x = 0 To XLength - 1
Dim SessionID As Integer = Integer.Parse(FileData(x, 0))
Dim IsValid As Boolean = True
[Code].....
Check Whether Image At Dataset Is Empty Or Not
Feb 14, 2009im getting a image from my database to a data set. before i convert it to a proper picture i need to check whether ds.Tables("userDetails").Rows(0).Item("photo") is EMPTY or NOT. How should i write the if condition? <code>If ds.Tables("userDetails").Rows(0).Item("photo")<> ??? Then
Dim pictureData As Byte() = DirectCast(ds.Tables("userDetails").Rows(0).Item("photo"), Byte())
Dim picture As Image = Nothing
Using stream As New IO.MemoryStream(pictureData)
picture = Image.FromStream(stream)
End Using
[Code]...
Checking DataSet For Null Before Referencing?
Oct 15, 2010I 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")
Checking For Duplicate Row In DataSet.RowChanging?
Feb 7, 2012I am using the DataSet to test for data errors on a DataGridView (to give the user feedback before they save changes back to the database). RowChanging event has the code at the bottom and this manages error messages on the DGV via an ErrorProvider. I want to add something to this code that esnures there are no duplicate rows (it's a 2 column table and one of those is the autoincrement PK). However I cannot work out how to do this and since the column in the database is set to Indexed (No Duplicates) it will throw an Ole error if I don't handle it, I could manage it in a Try block around TableAdapter.Adapter.Update but would prefer not to add needless round trips to the DB when it really ought to be simple to do it in the code (and preferably in the DataSet, not the form).
I found the following code (Forum Post) and try as I might I can't make it work since I can't get access to a DataTable within the RowChanging event that allows me to run DataTable.Rows.Find().
Dim expression as String
Dim matchingRow as DataRow
matchingRow = Mytable.Rows.Find(expression)
In my case:Mytable would be some kind of reference to the table / dataset etc.
'expression' would be e.Row.compclass.ToString
* a reference to the database table the form works with (bearing in mind that this code is in the DataSet not in the form). I've tried properties/methods of the DataSet itself; creating a new DataTable and linking it to the DataSet Table (or DB Table); creating
a new DataTable and loading it with the table contents - Searching MSDN and the forums hasn't popped anything up yet.I'm currently experimenting around this code:
Dim strCompClass As String = e.Row.compclass.ToString
strCompClass.Trim()
Dim foundRow As DataRow = ???.Rows.Find(strCompClass)
[code]....
This is the current code in the RowChanging event. The new code would be inserted after the last End If in the code below.
Private Sub ref_compclassDataTable_ref_compclassRowChanging(ByVal sender As System.Object, ByVal e As ref_compclassRowChangeEvent) Handles Me.ref_compclassRowChanging
If e.Row.HasErrors Then
[code]....
Dataset Rows Count Empty, But Table Is Not?
Apr 8, 2010MsgBox(MyDataSet.mytable.Rows.Count)
Gives 0, why?
The table has data!
Fill Empty Access Table From Dataset?
Jun 3, 2011I think this may be a usual issue but I am not able to find much info. There is a master customer database and a call log database at work. The call log database has two tables that are updated from the master database monthly. Now I am writing this vb frontend for the call log database and cannot figure out the update portion
For p = 0 To maxrowsC (currently around 1000 rows)
With myCommand.Parameters
.AddWithValue("@HEATSeq", dsCallLog.Tables("ConfigDS").Rows(p).Item(0))
[code].....
VS 2010 : Empty Dataset Conversion To Table?
Jan 13, 2012I inherited a program that retrieves 3 datasets from our vendors' web services, converts it to a table and then merges the 3 tables before exporting into xml from the resulting combined table. The problem I am having is that when web services returns an empty dataset the program crashes in the attempt to create a table from the empty dataset.How do I modify this code to either create an empty table or recognize the empty dataset and skip around that particular table creation, merge and removal? There is always data in at least one of the datasets.
foreach (Branch branch in branches)
{
Console.WriteLine("Opening connection...");
Vendor.ws_ordersSoapClient VendorClient = new VendorInterface.Vendor.ws_ordersSoapClient();
[code]....
VS 2008 Dataset - Checking If Date = Null?
Sep 7, 2009I 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.
Clear Dataset But Get Error Sometimes If It Is Empty When Try To Clear It?
May 17, 2009I have a timer that runs every time by itself, and for the code the runs in it I would like to have it clear the dataset before it does anything, the timer runs every 10 seconds, so I tried to do dataset.clear but it would crash if the dataset had no values
View 4 RepliesVS 2005 - Boolean Checking - Better Performance By Checking For A True Value
Aug 4, 2010Is there any better performance by checking for a true value like this:
[CODE]..............
Than like this:
[CODE]..............
DataGridView - Convert Nulls To Empty Strings And Display It In The Grid As Empty Strings
May 14, 2009I have a DataGridView that has some columns with dates. It binds to an in-memory Datatable which gets loaded from an string array of data passed back from the backend Some of the rows returned have nulls for the date columns. Solution 1: If I define the Date column in the DataTable as "string" I can easily convert those nulls to empty strings and display it in the grid as empty strings (desired results). However, if the user clicks on the date column header to sort by date, it doesn't order the rows as you want. You get a purely string sort order. Not acceptable
[Code]...
Nothing Equals String.Empty, Null Does Not Equal String.Empty?
Jun 28, 2010This must've have been asked before but I couldn't locate it. In a mixed code project (VB and C#) we were debugging some old Visual Basic code where a statement as follows could be found:
If Request.Params("xxx") <> "" Then
'do something
I considered this a bug as Request.Params could be null, in which case the statement would've become false which wasn't the idea. So I thought. I just found out, -- probably for the tenth time and I will keep forgetting -- that the following two statements are not equal, while Nothing in VB should be equal to null in C# (thought I):
if(String.Empty == null) // always false
If String.Empty = Nothing Then ' always true
Should I dismiss this as a typical Microsoft backward compatibility effort, or should I consider this a huge error in the VB.NET compiler? Does anybody know the Microsoftean opinion on this oddity?
Arrays - If Not String.Empty Ignoring Empty String
Aug 11, 2010I have a array of strings and I am looping through them, but the string might be empty so I am trying this:
[Code]...
DataSet Editor - Allows The User To Edit A DataTable In A Strongly-typed DataSet
Mar 15, 2010When the user clicks an "Edit" button on my form, I want a box to come up which allows the user to edit a DataTable in a strongly-typed DataSet. What's the best way to do this?
View 2 RepliesIDE :: Dataset Code Behind Datatable.ColumnChanging Event Firing / But Dataset.HasChanges Property Not True
Jan 28, 2010I have code running in the Datatable.ColumnChanging event in my dataset. This dataset underlies a form and conventional drag/drop controls are in place for data entry.when the event triggers and runs, I am running code in the form that checks the dataset.HasChanges property. It is showing False. But this is immediately after the ColumnChanging event has been triggered.Okay, I see by others posts and MSDN that .HasChanges will only be true after moving off the row with the changed column. I have also noted lots of discussion about the advanced binding property of DataSourceUpdate Mode, but that does not address this issue.I guess I can do this by checking the state of the row for the binding source. Just seems odd that the event behind the dataset can be triggered and that does not change the dataset.HasChanges property.
View 3 RepliesSystem.Data.Common.DbDataAdapter.Fill(DataSet DataSet)
May 14, 2012I have tried everything I can to get beyond this error which shows below as <<<<< error here. It is trying to fill a dataset from a data adapter. If I change the SELECT statement to just SELECT * FROM xTable I get the correct number of records in each table. But anytime I try with a more complex statement I get the error message shown below which indicates System.Data.Common.DbDataAdapter.Fill(DataSet dataSet. I've completely erased all data and entered a new set of test data so I know there is no problem with relationships. Each table has primary key which is foreign key in other table. IS there something wrong with the Imports section: Imports System
[Code]...
.net - Copy Data From Dataset To A Type Dataset Using Automapper?
Aug 24, 2010i am trying to copy data from a standard Dataset to a Type Dataset (XSD) of same table structure. i want to use Automapper to do that one. So how can i do that using automapper?
View 1 RepliesFill A DataSet On Application Startup And Use Dataset Other Form?
Jun 5, 2010I need to pick all data in my application from my database and use it in my form
my question : how to pick all data in my application then i use it
Loop Through Dataset Updating Data From Results Of Another Dataset
Jun 22, 2010I 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]
View 1 RepliesSaving Dataset To Database Which Has Imported Rows From Another Dataset
Jan 4, 2011I have a problem saving a dataset which contains rows that i have imported from another dataset. i can successfully view the imported rows in a gridview but i cannot commit the rows back to the database.
View 2 Replies
