im trying to select some rows based on a criteria, i was wondering is it faster if i create a dataview (based on the criteria) and then loop through the view? or should i loop through the entire datatable and check the criteria manually.
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every time i run this code i get the same error
Unable to cast object of type 'System.Data.DataTable' to type 'System.Data.DataView'.
the code is
Dim plmExcelCon As New System.Data.OleDb.OleDbConnection
Dim cmdLoadExcel As System.Data.OleDb.OleDbDataAdapter
Dim PrmPathExcelFile As String
[Code]......
How to create a dataview from a datatable?
What is the basic use of the created dataview?
If want to do a DataView.Find on a DataTable that is already 'ORDERED' by the Column I am seaching, so a DataView.SORT should not be necessary, but it throws an Exception if I don't give a .sort command before the .find command. Is there any way to avoid this apparant duplication ? and speed up the search time. Its a very large table - 1 million rows. I am using VB 2010
View 6 RepliesI'm loading a DataGridView from a DataView which collects data from a DataTable. I use the DataView to filter, this is the
Dim dv As New DataView
dv = DataSet4.Tables("TABLA1").DefaultView
dv.RowFilter = "propietario='" + NombrePro + "'"
[code].....
I have a function (on vb.net) to get a data from a XMLWebService:
[Code]...
i have bounded my listbox to a dataset the result is system.data.dataview not name of all my students. below is my code.
con = New OleDbConnection("PROVIDER=microsoft.jet.oledb.4.0;data source=d:
redata.mdb")
con.Open()
[code].....
I have a datatable and I apply a filter to the defaultview.rowfilter property of that datatable. If I then loop through the rows collection of the datatable, will I only be able to see those rows that the filter applies to, or will it loop through all the rows?
View 6 RepliesI want to loop through my datatable column called SDESCR and created a string that looks like this.
Dim labels As String() = {"North", "South", "East", "West", "Up", "Down"}
this is what i am trying and it is not working
Dim labels As String()
For Each row As DataRow In tablegraph.Rows
labels = labels " ' " + row.Item("SDESCR") + " ',"
Next row
Is there any way to create a total row at the last of grid view without using loop
I mean if I want to get the sum of a column of a datatable then can I do it without using loop.
I added this lines in the form load of DataGridPrinter by Merrion in the codebank..[code]Unable to cast object of type 'System.Data.DataViewManager' to type 'System.Data.DataTable'.
View 2 RepliesI have the following code that needs to connect to my four spreadsheets for FileName(). I havent built the loop yet for the other three, but I am so used to working with a variable. Is this the best way (datatable) to get a single cell from a spreadsheet and if so how do I view the data once it is in the datatable? Ideally I would like myDataArray(3) to hold the 4 cell values. Please help. I am stuck. I want to be able to get the cell value $K2 form each sheet without invoking Excel. I think I am close, but dont know how to get the data from the table. These four cell values will be displayed and then emailed to our Country Director.
[code]...
Looping through rows in a DataView
I have created a dataview from a datatable.
My question is how can I loop inside the dataview?
I know that in a datatable I can perform a loop like this:
For Each oRow as DataRow in iDataset.Tables("tableName")
Msgbox oRow(0).ToString
Next
How do i do that for a DataView?
I start by looping through a string array, parsing out the strings I want and saving them to a temp table (I believe this part is working).Then, I take a DataView of the tale to get only the unique values from the rows.Then, things get messy, I need to get these unique values into my dataset. I been trying to do so using the DataView and also by passing the View to a new temp table then looping the values into the DataSet
View 1 RepliesIs it possible to transfer all row data stored in datatable to arraylist without using a loop ?
View 12 RepliesI'm pulling data from my DB, adding it to a DataTable and binding that DataTable to my DataGridView. Before I bind the data, I need to change/remove some data. When I loop through the rows and use a Select Case, just for this column, it doesn't work. But if I use an If, it works fine. [Code] In the example above, the "Pass_Flag" row works just fine, but the "FailureCD" does not. But after the Select, with the If statement, it works. In the example, I'm casting the row as a string first and then an integer. I tried casting to an integer in the select case and it doesn't work either.
View 4 RepliesI get the below error Unable to cast object of type 'System.String' to type 'System.Data.DataTable'.This is the code I'm using
Dim str As String = String.Empty
If (Session("Brief") IsNot Nothing) Then
Dim dt As DataTable = Session("Brief")
If (dt.Rows.Count > 0) Then
[code]....
I want to find a particular ID in a DataTable, I am using a DataView to filter the results, but how do I know which row in the original table the filter view corresponds to? Any ideas? In know I could use LINQ but I don't think this would help either?
[Code]...
I have application in .net 2.0 in which I have a DataTable object globally in my application and have different dataviews in whole application.
When an action performed i have create many threads lets say 5 in which data is read from different dataview, meanwhile while 2/3 threads are reading data(not all 2 more left to read data) a thread write data in datatable. So we get exceptions like "Enumeration update" or "parameter not null" type.
I have use ReadWriteLock for this but do not find any luck it gets stop on ReaderWriterLock.AcquireWriterLock().
I am almost there but for some reason I don't find the answer to my issue. Here it goes. In my application I have a form which displays a data grid view with some info I get through XML from a web server. The data grid view have as first column a Check Box colum. The second column have the information I get into a variable (from cells), one by one, to pass it to the sub with the XML command.
What I want to do is to be able to select all the rows and send the cell info of the second row (only for the selected rows) to my sub which will execute once then send the second cell info and execute the sub and so on until all the loop is complete. Currently my code works only if I delete one row at a time (sending the XML code will delete the info in the web server and update the datagridview which in return will remove the item).
[Code]...
VB2010, MySql I have a dataview generated from a datatable using a rowfilter.I have event handlers listening to the dataview.listchanged event. To keep the datatable (in memory) in sync with the mysql database (on a remote server), i issue datadapter.fill commands every now and then, the objective being that only the changed rows in the datatable (as a result of the fill) would generate a listchanged event on the dataview.To my surprise the dataview_listchanged event fires after refresh by the dataadapter.fill method, however the ListChangedType it gives is: ListChangedType = reset. I would have expected a ListChangedType.ItemChanged for every changed datarow.Since the dataview is used to populate a large storage yard, i am now forced to repopulate the whole storage yard, which is a time consuming business.Is there a way to only generate DataView.ListChanged events for rows in the datatable that are actually changed by the datadapter.fill method?
View 2 RepliesFor my app users can enter a SELECT statement themselves. This can be any select statement at all, it will be mainly used for creating a quick view e.g. SELECT * from table1 LEFT OUTER JOIN table2 on table1.id = table2.id.
Whatever this select statement maybe I load it into a datatable (after checking for no nasty stuff of course) in vb.net. I want to know the table names so I can query the database again for validation purposes on things like datatypes etc.
da.SelectCommand = New SqlCommand(sqlStatement, tempDB.Connection)
da.MissingSchemaAction = MissingSchemaAction.AddWithKey
dt = New DataTable
da.Fill(dt)
For my app users can enter a SELECT statement themselves. This can be any select statement at all, it will be mainly used for creating a quick view e.g. SELECT * from table1 LEFT OUTER JOIN table2 on table1.id = table2.id.Whatever this select statement maybe I load it into a datatable (after checking for no nasty stuff of course) in vb.net. I want to know the table names so I can query the database again for validation purposes on things like datatypes etc.
da.SelectCommand = New SqlCommand(sqlStatement, tempDB.Connection)
da.MissingSchemaAction = MissingSchemaAction.AddWithKey
dt = New DataTable
da.Fill(dt)
I have imported:
Imports System.Xml.Linq
Imports System.Data.SqlClient
Imports System.Data.DataTableExtensions
[code].....
[code]This is my Code the error is Class 'System.data.datatable' cannot be indexed because it has no default property.. When i try this code in oledb it works but here it wont..
View 1 RepliesI have a page which lists all the files in a particular folder (all PDFs), using a data-table and gridview. I'm currently sorting this table by the filename (by using a dataview), which isn't that helpful, and I want the gridview of files sorted by the file created or file modified date (as recorded in Windows). If that's not possible, a second option would be to extract the date from the file name string (no problem doing that), and sort the dataview/datatable or gridview based on that.
[Code]...
I am trying to display value of the field ("UserID") for every row exists in datatable to checkboxlist(make the checkboxlist item selected).
I used for loop, but only the field value from last row of RoleUsers table is selected in the checkboxlist.
Here is my code
Private Sub DisplayRoleUser()
Dim conn As SqlConnection
Dim cmd As SqlCommand
[Code].....
I 'd like to enable the user to apply a custom filter to a System.Data.DataTable.At the moment I have a very simple function like this:
Dim result = dataTable.Select(txtUserInput.Text)
With the filtered results I'd like to do further operations(e.g. Database Update/Delete).Is an sql injection protection needed or is the "Select" function secure?
//Edit:Can the "select" function be abused to manipulate any data in the datatable, execute code, ...? If the only danger is that this function can return to much/to less data there is no problem. But if the data in the dataset gets corrupted it's a real problem.
I am trying to get the DataView from a linq query expression which is querying a typed dataset. The result lands in a type of System.linq.IOrderedEnumerable. But i'm not able to convert this type to a Dataview although a few examples on the internet say that AsDataView function shoudl work but could you please throw some light on why the method AsDataView is not exposed on the query.
[Code]...
How to create a Filter in Data Grid view.
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