tclientdataset - Developer IT

tclientdataset's delta property

- by Vijay Bobba

Hi, do any one know the how to clear the data in the delta of the TclientDataSet explicitly? without using applyupdates thanks in advance, Vijay.

Trapping errors in TClientDataSet.CommandText

I have a TClientDataSet connected to a TDataSetProvider, which in turn is connected to a TAdsTable. I set the SQL command and then open the ClientDataset something like this: try CDS.CommandText := 'SELECT * FROM tablename WHERE fieldname = 1'; CDS.Open except // trap exception here - this never gets executed! end; If the SQL statement in CommandText fails, however (syntax error or whatever) I get an exception within the Advantage code, but it never gets caught in my own exception handling code. Is there any way for me to trap this error and report it nicely to the user. Alternatively is there a way to verify the syntax of an SQL query before executing it? I'm using Delphi Pro 2009, and Advantage Local Server 9.

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Handling update errors in multiple records in the TClientDataset's ReconcileError method

- by Fabio Gomes

I'm trying to use the ReconcileError event to allow the user to correct the data after an update error which occurred in a specific record among others. Example: I have a dataset with one field and 3 records, this field have a unique constraint on the database, then I change one value to conflict when it reaches the database, then I call ApplyUpdates on the Dataset. This will generate an error (violation of unique constraint) in the provider and abort the applyupdates process, returning raAbort in the Action var of the ReconcileError method. In the ReconcileError method I tryied to use: Action := HandleReconcileError(aDataSet, UpdateKind, E); ** EDIT ** After debugging and dumping the DataSet records which were returned from the server, I noticed that there are 2 records in this Dataset, the first is the Old record and the second have all the changes I made to the first record. I'm a bit confused, will I always get this DataSet with 2 records? I thought that it should have only one record with the Old/New values. Thanks.

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to track the modified rows and manually update from the TClientDataSet's Delta

- by Vijay Bobba

hi, Is there any way to manually track the changes done to a clientdataset's delta and update the changes manually on to then db. i have dynamically created a clientdataset and with out a provider i am able to load it with a tquery, now user will do some insert update and delete operations on the data available in the cds, and at final stage these data(modified) should be post in to database by using a tquery(not apply updates)..

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Is it possible to use calculated fields in aggregated fields?

- by Jørn E. Angeltveit

Is it possible to use a calculated field in an aggregated field in a TClientDataSet? object cdsOrders: TClientDataSet AggregatesActive = True object cdsOrdersPrice : TIntegerField FieldName = 'Price' end object cdsOrdersCount: : TIntegerField FieldName = 'Count' end object cdsOrdersCalcTotal: TIntegerField FieldKind = fkInternalCalc FieldName = 'CalcTotal' Calculated = True end object cdsOrdersAggGrandTotal: TAggregateField FieldName = 'AggGrandTotal' Active = True Expression = 'SUM(CalcTotal)' end end

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"either bof or eof is true or the current record has been deleted.." error on applyupdates that cont

- by AhmetC

Hello, I am getting this error while resolving delete operation from ClientDatset to TAdoDataset (which bound to access table). I am using Delphi 2010. My DatasetProvider between TClientDataset and TAdoDataset : object dspTarifeler: TDataSetProvider DataSet = DM.qryTarifeler ResolveToDataSet = True Options = [poPropogateChanges, poUseQuoteChar] end Error occurs in this function which is called by TDataSetResolver.EndUpdate(); procedure TCustomADODataSet.InternalGotoBookmark(Bookmark: Pointer); begin Recordset.Bookmark := POleVariant(Bookmark)^; end;

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Delphi Clientdataset Lookup/Aggregate

- by TheRoadrunner

Hi, I need a little help with ClientDatasets in Delphi. What I want to achieve is a grid showing customers, where one of the columns shows the number of orders for each customer. I put a ClientDataset on a form and load Customers.xml from Delphi demo-data. Another ClienDataset is loaded with orders.xml. Relatively simple, I can define an aggregate on the orders CDS showing the total amount per customer (or the count). (See Cary Jensens article on this: http://edn.embarcadero.com/article/29272) The problem is getting this aggregate result from orders dataset into the customer dataset. It is kind of an reverse lookup, since there is a 1-n relationship between customers and orders, not an n-1 as normally in lookup scenarios. Any ideas ? Søren

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Are TClientDataSets part of your toolkit, or have they been replaced by something else?

- by Tom1952

I have 50 or 60 records of four or five fields. I need to load the records into RAM (From a CSV file), search on different fields, enumerate, etc. Not a lot of data, not a lot of functionality. I was all excited to use the new (to me in D2010) TDictionary or TList, but thought that a TClientDataset (which I've never used before) might be more appropriate. With a TClientDataSet, I can use .Locate on any field, enumerate with while NOT CDS.EOF, etc. And, what exactly is this MidasLib that I have to use with CDS? Can I reasonably expect it to be supported in the future? Is TClientDataSet still considered state-of-the-art, or is it showing its age and somewhat deprecated (literally and figuratively)? I've seen colleagues use DX's TdxMemData. Why use it (or any of the other handful of memory datasets I've seen while googling this issue) rather than a CDS? Related question: http://stackoverflow.com/questions/274958/delphi-using-tclientdataset-as-an-in-memory-dataset

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unable fire an event for dynamically created component

- by Vijay Bobba

hi, I have created a dynamic TClientDataSet component and tried to fire the OnCalcFields event....it has'nt worked. The code looks like this... table := TClientDataset.Create(Application); table.OnCalcFields := tableCalcFields; where tablecalcfields is the method defined by me. thanks for answers, Vijay

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Temporary table resource limit

- by Jk

Hi, i have two applications (server and client), that uses TQuery connected with TClientDataSet through TDCOMConnection, and in some cases clientdataset opens about 300000 records and than application throws exception "Temporary table resource limit". Is there any workaround how to fix this? (except "do not open such huge dataset"?) update: oops i'm sorry there is 300K records, not 3 millions..

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