Well, the TClientDataSet already have this function. So use your TSQLDataset -> TDataSetprovider ->TClientDataSet

The comments below seem to point to a product that is a TDataset descendant that serves up a dataset built by running normal SQL queries against one or more other TDataset descendants. Conceptually very powerful. This would be similar to a product named TxQuery (http://code.google.com/p/txquery/), which is not maintained that much anymore. The competing product AnyDAC (now FIreDAC) I believe has a more stable and maintained version of this idea (not sure -- don't have it). We would like to see such a component in UniDAC. Even if SQLite supports this, a component that wraps the static SQLite up with a simple interface might still be useful.

Already possible with SQLite. With SQLite, one can even do a "hot backup" of the in-memory database, as one way to save it to disk.

A little local in-memory SQL server?
Something like SQLite ':memory:'?
It would be nice but I think it would be a lot of work.
Maybe with a reduced SQL set?

i need a virtual dataset where you can run sql commands like count, sum, order by, group by , ... . It is possible to create custum sort and count code on a virtualtable, but using SQL commands is much easier and less time consuming.

Before I assign any votes to this item, can we get a clarification on what it will be...

Apart from what is already described, will this dataset support further trimming the dataset with actual SQL statements -- if my memory dataset contained 600 records, could I set a SQL statement (not a filter) to select 8 rows and have the dataset serve up those 8 rows to say a grid?

I'm looking for a complete in memory database solution where user will be able to create at design/runtime memories databases and/or memories tables.
Tables should be imported/created from existing dataset.
Tables should be joined (left / riht / inner) with other tables
I'm aware that all of this represent a lot of work.

DAC components have in memory Dataset: TVirtualTable. TVirtualTable has properties Filter and Filtered that allows to filter rows that is equal to query: SELECT * FROM TABLE WHERE <Filter>.

Please describe the functionality you need in more details.

If you need Master-Detail releation between TVirtualTable then please vote here: http://devart.uservoice.com/forums/104635-vcl-data-access-components/suggestions/1583191-improve-tvirtualtable?ref=title