Is there some absolute requirement that it all be done in SQL? Depending on the number of "items", it'd probably be faster in a loop in code.
Even in MSSQL Server using TSQL, you're better off using a cursor for that sort of thing. I only use UPDATE FROM when I need a join to formulate the WHERE clause. > On Jun 4, 2016, at 12:18, skywind mailing lists <[email protected]> > wrote: > > Hi, > > why? At the moment I have to run something like: > > UPDATE A SET item1=(SELECT B.item FROM B WHERE B.ID=A.ID),... itemN=... WHERE > EXISTS (SELECT 1 FROM B WHERE B.ID=A.ID); > > Using a FROM clause I just need one scan through B (at least in principle). > Now, I need N+1 scans. > > Regards, > Hartwig > >> Am 2016-06-04 um 15:33 schrieb Gerry Snyder <[email protected]>: >> >> If SQLite implemented the FROM it would just be a translation into the >> complex and slow statements you want to avoid. >> >> Gerry Snyder >> On Jun 4, 2016 9:19 AM, "skywind mailing lists" <[email protected]> >> wrote: >> >>> Hi, >>> >>> I am using quite often SQL statements that update the data of one table >>> with data from another table. This leads to some quite complex (and slow) >>> statements because SQLite3 is not supporting a FROM clause in update >>> statements. I am just wondering why the FROM clause is not supported by >>> SQLite3?! Is this too complex to implement or is there simply no demand for >>> these type of statements? >>> >>> Regards, >>> Hartwig >>> >>> >>> >>> _______________________________________________ >>> sqlite-users mailing list >>> [email protected] >>> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >> _______________________________________________ >> sqlite-users mailing list >> [email protected] >> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list [email protected] http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
