IDE :: Dataset Code Behind Datatable.ColumnChanging Event Firing / But Dataset.HasChanges Property Not True
Jan 28, 2010
I 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.
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Sep 21, 2009
When you edit a cell in a datagrid, how can you "commit" that change if you are still in that current cell? Right now, the DataSet.HasChanges property isn't true UNTIL you leave the current cell. If you don't click on another row, then the property is not true yet. How can I tell it that it is true without physically clicking on another cell?
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Feb 13, 2012
I have an ErrorProvider on a form with a DataGridView.The Binding Source for the DGV points at a single table in the DataSet (which hooks up to an underlying Access DB).The table has two columns:
1) Autoincrement PK
2) Text field, <=25 chars, unique, can't be Null or empty string
I test for string length (>0 and <=25) in the DataSet.Table.RowChanging event.If it's out of range then I use e.Row.SetColumnError, that passes the error to the ErrorProvider / DGV on the correct row and DataSet.HasErrors returns True. All good, no problems.
I test for uniqueness in the DataSet.Table.ColumnChanging event.If it's not unique I can set the error with either e.Row.SetColumnError or e.Row.RowError; Now it gets complicated since sometime this makes the ErrorProvider / DGV show the error and sometimes not, it depends on whether the DataSet keeps the Unique = True constraint of the underlying DB.
Why would I have the DataSet be False for Unique when the DB is True for same constraint? So that the user interaction with the form has the minimum of dialogue box based interuptions. I am trying to design a system whereby all issues / errors are reported
to the user as they interact with the form in a subtle way, allowing them to keep working but trapping errors before any attempt to Save from the DataSet to the DB.
So, if the DataSet keeps the unique constraint then when you insert the new (duplicate) row the DGV throws its DataError event, a default dialogue appears, behind which the DGV has the ErrorProvider icon on the correct row. However, since the DataError event
causes the problematic change to be rolled back, the new row is removed and the error disappears.
If I change the DataSet requirement to Unique = False, then SetColumnError does not cause an ErrorProvider icon to be shown and DataSet.HasErrors returns False. I can improve upon this slightly by using RowError, this causes DataSet.HasErrors to return True but the ErrorProvider icon still does not show.Further, when using Unique = True on the DataSet, and editing an existing row to be a duplicate of another, the behaviour is the same, DGV.DataError event, roll back of the change but the ErrorProvider icon remains, despite the row no longer being a duplicate and DataSet.HasErrors returns True. The text of the the ErrorProvider tooltip is the one from SetColumnError, not RowError.So, the behaviour of SetColumnError is affected by the state of the DataSet field Unique constraint?
Unique = True
SetColumnError affects the DGV / ErrorProvider and DataSet as expected.
(RowError behaviour unknown)
Unique = False
[code]....
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Aug 13, 2010
I tied a text box to dataset using the following code
tbAddr.DataBindings.Add("Text", dsCust, "SYS_CUSTOMER.Address");
gridview to same dataset using
dgvNames.DataSource = customerBindingSource - this is in property box.
customerBindingSource.DataSource = dsCust.Tables["SYS_CUSTOMER"];
i make changes in text box tbAddr update_click () in this method i use the following code
[Code]...
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Apr 13, 2011
Update problem : When i check DataSet.HasChanges() it return false, unless position change (move next or previews) it return True.
After position changes every things is OK and updated!!
this is the
PHP
Private MyAdapter As New OleDbDataAdapter
Private MyDataSet As DataSet
[Code]....
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Mar 15, 2010
When 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?
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Jul 21, 2011
I'm working on a helper class that will make things easier for me when connecting to and viewing a crystal report.Now I need to create a Property called DataSource. Crystal has a SetDataSource method that has 4 overloads/constructors(not sure what the right term is)1 accepts a System.Collections.Ienumerable, the 2nd accepts a Dataset, the 3rd a DataTable, and the 4th a DataReader.Now I want my property to be able to accept all those. So what Type must my property be.If I can just have DataSet and DataTable for now it would be fine, as I work with those mostly Public Property DataSource as?
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Dec 15, 2011
I have connected my sql db with vb and I m trying to make a UI. My question is that when I write code in order to create datatables and I fill them with the results of queries I've created, where do these datatables belong? I'm wondering if I have to define a new dataset or do they belong to the existed dataset which is created by the dataset configuration wizard??
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Mar 23, 2010
1. Can someone show me sample codes on how to do that ?
2. I encountered a problem with the INSERT sql statement. I keep receiving syntax error in insert statement exception. Is there anything wrong with the statement ?
[code]...
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Nov 27, 2010
I have a listbox binded to a list of objects. For each list item I wanted to have a rectangle whose fill color is determined by a few properties of the binded object. So I did the following:
Made sure INotifyPropertyChanged was implemented on my object.Created a class to expose the properties I am interested in as attached properties.Binded the properties of the object to the attached properties of the rectangle Created a style that uses triggers to set the rectangle fill based on attached properties.
This works, but only the first time the property of the object changes. After that, the attached properties do not seem to be receiving notification when the data object's property changes. I have double checked and my data object is raising the INotifyPropertyChanged event.
<Rectangle Style="{StaticResource RecordStateRectangleStyle}"
Width="10" Height="10" Stroke="Black"
local:RecordAttachment.RecordState="{Binding Path=RecordState}"
local:RecordAttachment.IsDeleted="{Binding Path=IsDeleted}" />
[code]....
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Dec 15, 2011
I would like to get message, or true result when DataSet get new record (new row). But, I always get message as "no". [code] Button3 should return "Yes" as new record has been added, but does not? [code]
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Oct 31, 2010
how to copy data from datatable to table in dataset i ry this but its readonly property
ds.datatable1=newdt.copy
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Jul 29, 2010
I have build a datatable in vb
dim Booking_table as datatable
Is it possible to add this datatable to a dataset or do I have to build in acces2007 and import in VB.
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Nov 4, 2010
I have a strongly typed dataset and datatable and I am trying to do an add row.
Dim newDT As New hdar.AccessRequestsDataTable
Dim newRow As hdar.AccessRequestsRow = newDT.NewAccessRequestsRow
newRow.Number = nextNumber
newRow.RequestedByID = Me.cboUser.SelectedValue
newRow.RequestedOn = Date.Now.ToShortDateString
[Code] .....
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Apr 27, 2012
i am using Microsoft.Office.Interop.Excel to read the data from excel,
--Students_Table--
id_S | Name | Sex
12 john M
[code]....
-----the table where uploaded excel file saved--
id_u | id-S | Scor |
1 12 30
i want to get the Id_S from "John"(excel file), i tried using the dataset with query
select Id_P from Students_Table where (Name =: Name)
and then check fillBy & GetBy my vb code :
Dim ta As New Students_TableAdapters.StudentsTableAdapter
Dim DataID as Integer
if ta.fillBy(ExlRead.Value) <> 0 then
[code]....
i use breakpoint to check those and i found an error message
"ORA-01722: invalid number"
(i'm using oracle database)if i pointed my cursor to the ta.fillBy it shows Public Overridalle Overload Function FillBy(Name as string) as decimal?
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Jul 27, 2010
I have a dataset and inside of it theres two(2) datatable. Is it possible to do this kind of query.
"SELECT DATATABLE1.NAME FROM DATATABLE1 INNER JOIN DATATABLE2 ON DATATABLE1.ID = DATATABLE2.ID"
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Jan 12, 2012
This error is occuring while adding one datatable from a dataset to another ."DataTable already belongs to another DataSet."
dsformulaValues.Tables.Add(m_DataAccess.GetFormulaValues(dv.ToTable.DefaultView.ToTable(False, strSelectedCols)).Tables(0))
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Jun 16, 2010
I am trying to put a datatable into a dateset, which I then export to a CSV file. I am getting this error
DataTable already belongs to another DataSet. on the following line dsExport.Tables.Add(dtExport)
VB
Using dtExport As DataTable = DirectCast(dgvSafetyGlasses.DataSource, DataTable)
[Code]....
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Mar 16, 2009
I am ably to load a XML file (via a filepath) to a datatable. See code below.However, I'd like to be able to load a in-memory XML document to a datatable.
Code: Public Function XmlToDataTable(ByRef filePath As String) As DataTable
Dim ds As New DataSet Dim dt As New DataTable ds.ReadXml(filePath) dt = ds.Tables(0).Copy()
Return dt
End Function
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Dec 26, 2011
I used to do all the database logic with SqlCommand and the Methodes ExecuteReader and ExecuteNonReader and never used something like DataSet or Datatable.
Dim dbcon As Data.Common.DbConnection
Dim cmdselect = dbcon.CreateCommand()
cmdselect.CommandText = "SELECT * FROM users WHERE id = 1"[code]...
This is sometimes hard to administrate. So I would like to use a more efficent way. May thought was to Query a DataTable, make changes to it and then call .AcceptChanges and all changes where wrote back to the Database. But this seems not to be the way it works?The method .Update requires that i bring with my own update command, if i have to do that myself, why using the datatable, dataset... anyway?How do you write your DB Backend?
With SQLCommands arrays and variables?
With DataSet, DataTable?
With a VisualStudio genereated template?
With Linq?
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Dec 23, 2011
I am using strongly typed dataset and have many tables in that. The problem is now I want to filter data from
GetData()
function which has a query like
select * from table_name
How can I filter a particular table and distinct values from it. Also if I try to filter it return all column but rest have null values except the one I asked, so I cannot assign it as a datasource to a datagrid or combobox. How can I do this..
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Jun 5, 2011
I need to convert bindiangsource.datasource (which is a list) to dataset or datatable.
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Jan 2, 2010
How to create a dataview from a datatable?
What is the basic use of the created dataview?
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Dec 31, 2011
I am new to vb.net and I am trying to query a database and print out the records in the row to the console window. I got it to work, but I have a feeling that there is a more concise way to do this. One thing that I am sure is wrong is that I had to convert the dataset to a datatable to be able to retrieve the values. Is that correct? Could you take a look at the code below (especially the for loop) and let me know what I can improve upon?
[Code]...
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Aug 2, 2009
this code:
If Not DataSet1.Tables.Contains("Table0") Then
DataSet1.Tables.Add(New DataTable("Table0"))
End If
[code].....
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Nov 4, 2009
asn1.htm (14.26K)
Number of downloads: 248Private Sub Command1_Click()
Dim HTML As HTMLDocument
[Code]......
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Sep 15, 2010
I've been fighting with this problem for 2 weeks now and haven't been able to figure it out to parse data from a text file to a datatable using SteamReader. I am trying to import the data like it is displayed in the datatable into SQL Server 2005, I have tried using sqldataadapter approach, the standard approach, ADO.NET approach. [code]...
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Mar 27, 2009
I have returned xml data in a variable and need to loop through the returned xml and pull certain data from select nodes.
I was thinking the best way would be to load into a dataset (or datatable) and loop through that.
I also have the xmlschema. What's the best way to code this?
I thought I could do something like so but it gives me the following error: DataTable 'newdt' does not match to any DataTable in source.
[Code].....
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Apr 20, 2011
I am trying to update mysql table from a txt file using vb.net. So far I've found code here and there and been able to extract the data from the txt file, now my question is how to update mysql from the same dataset or xml file. Here is my code to populate the datagrid/dataset/xml file.what is the easiest way to update mysql assuming "Orden" is my primary key in mysql.
OpenFileDialog1.Filter = "Text File|*.txt"
OpenFileDialog1.Title = "Open File..."
OpenFileDialog1.FileName = "trackings"
[code]....
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Nov 18, 2009
I've been using VB for some time now, but I must admit I am a little confused. I started learning with 2002, then 2003, 2005 and now 2008. I think database coding must have been going through a kind of transition when I was trying to teach myself the basics. As a result, I am not entirely clear on a few things..
1) What's the difference between a DataTable and a DataSet. Why would I use one over the other?
2) Personally I dislike using DataAdapters etc and much prefer typing my connections in code so I can see what's what. When using the visual tools things are 'hidden' from view and it's not clear what's going on - do others find the same or is this just me being old fashioned?
3) Using my code-based approach (ie: creating SQL connection, using ExecuteNonQuery and a SQLDataReader to read the results into my application) - is this less efficient than the alternative methods?
4) Finally...LINQ. Is it any better and should I be using it as standard practice?
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