Hello,
are you actually looking for an unqiue key or number? Like an unique order number? If yes, is a generator an option? If it's not go for the recommendation of fabianoaspro and put ROWS 1 in the select statement. This gives you only one record. Niko Von: firebird-support@yahoogroups.com [mailto:firebird-support@yahoogroups.com] Im Auftrag von skander_sp Gesendet: Dienstag, 16. April 2013 09:58 An: firebird-support@yahoogroups.com Betreff: [firebird-support] AGAIN (i know, but different) Max optimized... or not? Easy (and usual case) Simple table CREATE TABLE ORDENES ( ID_ORDEN INTEGER NOT NULL /* Primary key - GenId */ YEAR_ORDEN INTEGER NOT NULL /* Year of Orden */, N_ORDEN INTEGER NOT NULL /* Order in the Year */, ... /* no matter */ ); ALTER TABLE ORDENES ADD CONSTRAINT UK_ORDENES UNIQUE (YEAR_ORDEN, N_ORDEN)USING DESCENDING INDEX UK_ORDENES_YEAR_N_ORDEN; Now I need to access in the insert trigger, for next order to be assigned to N_ORDEN in the YEAR_ORDEN using select coalesce(max(o.n_orden),0)+1 from ordenes o where o.year_orden=new.year_orden into new.n_orden IT WORK!!!! nice, BUT NOT OPTIMIZED, in the Performance Analisys it read (indexed) all the N_ORDEN in the table, not going to the first (given the descending order of the index) How can optimize the index/query? Or simply is not possible doing more? Tks in advance [Non-text portions of this message have been removed]
