Hi, I have the following schema:
> CREATE TABLE aliases (name text not null, assignedTo text, validFrom integer > not null); > CREATE TABLE services (name text primary key, url text not null, type text > not null); > CREATE VIEW latest_aliases as select a.name, a.assignedTo, a.validFrom from > aliases as a join (select name, max(validfrom) as mvf from aliases where > validFrom <= strftime('%s', 'now') group by name) as b on a.name=b.name and > a.validFrom=b.mvf; > CREATE VIEW alias_info as select a.name, s.url, s.type from latest_aliases as > a join services as s on a.assignedTo = s.name; The aliases table maps names to services at different times. So for example with the following data: > sqlite> select * from services; > svc1|http://somewhere|type1 > svc2|http://somewhere.else|type1 > sqlite> select *,datetime(validFrom, 'unixepoch') from aliases; > env1|svc1|1342967110|2012-07-22 14:25:10 > env1|svc2|1342967185|2012-07-22 14:26:25 I want env1 to be mapped to svc1 after 14:25:10, until 14:26:25 after which point I want it to be mapped to svc2. This is done with the latest_aliases view, alias_info just joins latest_aliases to the services table to get the connection info. However, I'm quite concerned about executing strftime('%s', 'now') inside the subquery, specifically does it execute multiple times? I don't want this to happen because it could cause a rare bug when the list of services returned is partly pre and partly post an update. I'm trying to convince myself that the subquery in latest_aliases only executes once, and also that alias_info only runs latest_aliases once. However, I'm not doing very well at convincing myself. Can someone confirm this is true, or suggest a nice solution to get the current time function out of the when clause. Thanks, Kevin Martin. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users