Given that a query needed to return data for a page of a grid is of the form
SELECT FIRST 25 SKIP <some multiple of 25> <some table>.ID (and some other fields of human-readable data) FROM < <some table> plus tables as needed for other fields in the SELECT, WHERE and ORDER BY clauses> WHERE <something, may be complex expressions involving several fields> ORDER BY <something else, may be several fields> how can I find out what <some multiple of 25> is for a given <some table>.ID? (Without using any features that are only in Firebird 3, which are needed for the solutions I've found so far. Surely this is not a rare thing to want to be able to do?) Scenario: Data is displayed in a grid in the user interface, with 25 records per page. The user gets to specify the filters (WHERE) and sorting (ORDER BY) in the user interface, ie these change outside my control (and in consequence appropriate tables get pulled into the FROM clause as necessary by the query generation code). The wanted operation is that the user can say "show me the record with ID such-and-such" (by doing something in some other part of the UI), and the grid will display the correct page of data (and then scroll as necessary and highlight the wanted record, which obviously we'll have to do in the UI). In, that is, a sane amount of time - fetching hundreds of pages of data to the grid sequentially until the right record appears is not a reasonable solution! ID may or may not be the primary key, but we can use an indexed unique field if that helps. -- Tim Ward
