when i am adding second table(dtResult) to data set that time it's giving error
A DataTable named 'Table' already belongs to this DataSet.
DataTable dtSession = new DataTable();
DataTable dtResult= new DataTable();
dtResult.TableName = "A";
dtSession.TableName = "B";
dtSession = objOpt.GetSearchDetails().Copy();
ds.Tables.Add(dtSession);
dtResult = objOpt.Search_Synchronous().Copy();
ds.Tables.Add(dtResult);
Thanks in advance
You need to name the tables after getting the copy from your method and before adding it to the DataSet.
DataTable dtResult= new DataTable();
dtSession = objOpt.GetSearchDetails().Copy();
dtSession.TableName = "B";
ds.Tables.Add(dtSession);
dtResult = objOpt.Search_Synchronous().Copy();
dtResult.TableName = "A";
ds.Tables.Add(dtResult);
Since you are getting the copy from your methods objOpt.GetSearchDetails().Copy() and objOpt.Search_Synchronous().Copy(), they are overwriting the names assigned to the table previously, and both of these are returning the table with name Table, that is why you are getting this error
I was getting this exception today, but it had nothing to do with adding a DataTable.
I have an ASP.Net Core WebApi, and in the Post and Put endpoints, I was attempting to save/update the new record and also search in the database (in the same table) for an existing record with the same details, and if such a record exists, to update it.
I was getting that exception when it tried to save these changes.
The solution was to split it up, save the new/updated record first...
// Avoid an "A DataTable named 'Users' already belongs to this DataSet." exception
await _context.SaveChangesAsync();
... and then check for an existing record, update it if necessary, and then doing a separate save...
await _context.SaveChangesAsync();
Yup, it's weird, but saving twice fixed this issue for me.
(I appreciate that this doesn't answer this exact StackOverflow question, but for anyone stumbling onto this page when they hit this strangely-worded exception, this'll be a lifesaver !)
I received this error when running command.ExecuteDataSet on a stored procedure where I declared a table variable then queried that table multiple times to return several datatables in the dataset. Because each datatable was queried from the same table, they all had the same name '#t'. I was able to resolve it by creating multiple table variables with different names in the stored procedure.
Related
I have a dataset called "titulos" and have 1 table there called "tb"
with the columns with the name "titulo","titulo 2" and "titulo3".
I'm trying to do an insertion of rows in the event onclick of a button
but for some reason my code doesn't work!
My dataset is on a xsd file and I am using visual studio 2013 with c#.
I already tried this code but I don't know how to apply in my situation:
NorthwindDataSet.CustomersRow newCustomersRow =
northwindDataSet1.Customers.NewCustomersRow();
newCustomersRow.CustomerID = "ALFKI";
newCustomersRow.CompanyName = "Alfreds Futterkiste";
northwindDataSet1.Customers.Rows.Add(newCustomersRow);
The problem is that shows an error saying it does not recognize the dataset...
The erros is : "The name " Ds_Admissibilidade" does not exist in the current context
A DataSet is a disconnected copy of the data. It forgets if the data originated from database, an xml file or anything else. When you add rows to the DataSet, you only change the in-memory copy, not the original source.
You need some mechanism to update the source. For databases, a table adapter or dataadapter will do this for you. For a file source, you need to serialize the DataSet to the file, much the reverse of the way you read in in first place.
Hope this helps :)
DataRow newRow = titulos.Tables["tb"].NewRow();
newRow["titulo1"] = "titulo1";
newRow["titulo2"] = "titulo2";
newRow["titulo3"] = "titulo3";
titulos.Tables["tb"].Rows.Add(newRow);
Make sure you're setting all the values of the non nullable parameters. If you're using another instance of the dataset "titulos" use ImportRow instead of Add function.
i have a strong typed DataTable named Account wich i sorted on Account.FullName:
DataView dvAccount = new DataView(dtAccount)
dvAccount.Sort = "FullName desc";
The fullname is a generated field from my DataSet after my query, based on first name, middle, last etc. This means that sorting by SQL query is not an option unfortunately.
First i tried to get the table like this:
dtAccount = dvAccount.Table()
But this gave me the original Table the Dataview was based on. So after reading online i found out that i should have used the DataView.ToTable() function instead of the DataView.Table() function:
dtAccount = dvAccount.ToTable() as dsAccount.AccountDataTable; // returns null
dtAccount = ((dsAccount.AccountDataTable) dvAccount.ToTable()); // gives Convertion to Typed Datatable Error
Now i get the problem that my Account Table is Strong typed. so searching online tells me that i could go with the DataTable.Merge() Function or DataTable.ImportRow() for each row but these are told to be a very heavy procedures because every row gets checked on the Type. what's the best practice solution to this situation?
I just had the same issue. I used this kind of solution.
dtAccount = New dsAccount.AccountDataTable;
dtAccount.Merge(dvAccount.ToTable());
This works fine for me.
Tell me if you have a better one.
According to this article : http://msdn.microsoft.com/en-us/library/xzb1zw3x.aspx , after I insert/change data in the dataset, I need to call the UPDATE to synchronize my database data with the dataset data.
My problem is this:
I have created a dataset called dataset1.xsd and then I create a new TableAdapter to do my INSERT query with, and THEN I need to somehow let my database know that the stuff in dataset has changed.
DataSet1TableAdapters.reservationsTableAdapter ta = new DataSet1TableAdapters.reservationsTableAdapter();
ta.Insert(LastName,Arrival,Departure); // this is where I do the INSERT query
Now I should update the dataset, right? How do I do this? The article I posted above suggests doing something like this:
ta.Update(DataSet1.reservationsDataTAble);
However, I can't do this because:
Error - 'myproject.DataSet1.reservationsDataTable' is a 'type', which is not valid in the given context.
I tried declaring a new Dataset1 DataTable, and then updating that, but it still won't show any changes in my database.
I KNOW, however, that the changes are saved in the DataSet, because when I fill a new datatable later, the record is there.
EDIT: Thanks to the comments, below, I tried doing this for a change:
DataSet1.reservationsDataTable NDT = new DataSet1.reservationsDataTable();
DataSet1TableAdapters.reservationsTableAdapter ta = new DataSet1TableAdapters.reservationsTableAdapter();
ta.Insert(LastName,Arrival,Departure);
ta.Fill(NDT);
ta.Update(NDT);
... and I could see (in the debugger) that the NDT datatable DID in fact contain the data that was "INSERTED" and then filled into the data table.
However, the ta.Update(NDT); still did not update my database...
I assume that However, the ta.Update(NDT); still did not update my database means that no sql-insert is executed and that yo get no exception.
does this work for you?
var myDataSet1 = new DataSet1();
var newReservation = myDataSet1.reservations.NewRow();
newReservation.LastName=...
newReservation.Arrival=...
newReservation.Departure=...
myDataSet1.reservations.AddreservationsRow(newReservation);
var ta = new DataSet1TableAdapters.reservationsTableAdapter();
ta.Update(myDataSet1.reservations);
I'm trying to edit the data in a dataset (change the value in a column on one row), which is not linked to a database. I've been googling for about an hour with no results and no good examples out there. Hopefully someone can help me.
My table (DataTable1) has these columns - ThreadID (string, PK), StatusText (string).
I can select a row in a DataGridView, and get the ThreadID value. No matter how I've tried to edit the row in the associated dataset, either nothing happens or I get an error. Here's what I have now:
string sThreadID = "";
sThreadID = gridThreads.Rows[gridThreads.CurrentRow.Index].Cells["ID"].Value.ToString(); // gives me a good id, which is in the dataset
DataRow drRow = dataThreads.Tables["DataTable1"].Rows.Find(sThreadID);
drRow["StatusText"] = "Test";
The error I get when getting the row (3rd line) is: "Object reference not set to an instance of an object.". I can't create a new DataRow object because there's no public constructor for it (according to my research).
I'm sure I'm missing something basic, but I'm not familiar with working with datasets. What am I doing wrong? Thanks for your help.
How does drRow know what "statusText" is? You may be only getting a shalllow copy, try cloning/copy so that the data types of the row get copied as well. Just an idea.
Does it happen that dataThreads or Tables["DataTable1"] is null ?
To create a new row, use the NewRow() method of the data table.
I'm attempting to pull some data from a SQLite database so that I can populate a GridView in my GUI: here is the code that returns the DataTable:
DataTable table = new DataTable();
SQLiteDataAdapter adapter = new SQLiteDataAdapter(this.command.CommandText, this.connection);
adapter.Fill(table);
return table;
For some reason after calling adapter.Fill, the DataTable is still not populated with anything. So far I've verified that the command text is correct and that the connection contains the correct connection string. Both are used successfully in other parts of the application. No exceptions seem to be thrown... Is there any place else I should be looking for trouble? Am I using the API incorrectly?
Thanks!
This looks like correct usage.
One thing to check -- after the fill you say the datatable is not populated. Were you just checking Rows.Count? What about columns? If the Fill creates columns to match your SELECT statement, but there aren't any rows, then you know the code is working but there's a problem with either your query, or you're not hitting the same database you think you are.
Is there a constructor that lets you just pass in the command directly?