> BEGIN; > SELECT COUNT() FROM <table> WHERE <condition>;
> if count == 0 > raise exception > else > UPDATE ... > COMMIT I have passed the query for count to sqlite3_exec () function. Return of count value is part of callback function or I need to use some other way to get. Cheers - Techi On Fri, Aug 2, 2013 at 4:53 PM, Hick Gunter <h...@scigames.at> wrote: > Please note that you do need to have an explicit transaction in progress. > Otherwise the SELECT may count records that no longer exist when the UPDATE > starts. > > -----Ursprüngliche Nachricht----- > Von: techi eth [mailto:techi...@gmail.com] > Gesendet: Freitag, 02. August 2013 13:13 > An: General Discussion of SQLite Database > Betreff: Re: [sqlite] Where Clause > > I was checking for Update only if condition will match. > > In fact it can be any operation like SELECT,INSERT,UPDATE or DELETE > > I think hint given by you using count() function will do the required. > > So here If condition matches then count will return nonzero value & based > on that I can continue further. > > Thanks > > > On Fri, Aug 2, 2013 at 4:15 PM, Hick Gunter <h...@scigames.at> wrote: > > > Please describe in simple words what you are trying to do. > > > > UPDATE <table> SET <field>=<value> WHERE <condition> > > > > Will change the value of <field> in all records of the <table> that > > satisfy the <condition>. > > > > You seem to be expecting that the field is changed also in records > > that do not satisfy the condition. > > > > Or perhaps you really want something like: > > > > BEGIN; > > SELECT COUNT() FROM <table> WHERE <condition>; > > if count == 0 > > raise exception > > else > > UPDATE ... > > COMMIT > > > > -----Ursprüngliche Nachricht----- > > Von: techi eth [mailto:techi...@gmail.com] > > Gesendet: Freitag, 02. August 2013 12:36 > > An: General Discussion of SQLite Database > > Betreff: Re: [sqlite] Where Clause > > > > Is their any Query format which can change the value based on > > conditional expression is TRUE!!! > > > > Thanks.. > > > > Techi - > > > > > > On Fri, Aug 2, 2013 at 2:11 PM, Hick Gunter <h...@scigames.at> wrote: > > > > > The SQL you gave translates to > > > > > > "Change the 'Name' field to have the value 'test' in all records > > > where the 'ID' field has the value 2". > > > > > > If there is no such record, then SQL has nothing to do and very > > > successfully does exactly nothing. > > > > > > SQL is "set oriented" and update operations on empty sets always > succeed. > > > > > > I guess you are thinking along procedural/file oriented lines as in > > > pseudocode > > > > > > record.id = 2; > > > error = readwithlock( file, byID, &record ); > > > if (error) raise exception; > > > record.name = 'test'; > > > error = updatewithunlock ( file, &record ); > > > if (error) raise exception; > > > > > > SQLite implements UPDATE as a SELECT followed by REPLACE statemenst > > > as if written like > > > > > > (INSERT OR) REPLACE INTO table SELECT id,'test' FROM table > > > WHERE id = 2; > > > > > > Which is equivalent to (naïve, not using index) pseudocode like > > > > > > open( file ); > > > while (! eof( file ) ) > > > { > > > error = readseqwithlock( file, &record ); > > > if (error) raise exception; > > > if (record.id == 2) > > > { > > > record.name = 'test'; > > > error = updatewithunlock( file, &record ); > > > if (error) raise exception; > > > } else { > > > error = unlock( file ); > > > if (error) raise exception; > > > } > > > } > > > > > > HTH > > > Gunter > > > > > > -----Ursprüngliche Nachricht----- > > > Von: techi eth [mailto:techi...@gmail.com] > > > Gesendet: Freitag, 02. August 2013 10:15 > > > An: General Discussion of SQLite Database > > > Betreff: [sqlite] Where Clause > > > > > > Come across one issue with conditional query execution. > > > > > > Query: UPDATE COMPANY SET Name= 'test' WHERE ID = 2; According to my > > > understanding if no ID = 2 is present in table then error should > > > return but it return with SQLITE_OK however Name value is not changed. > > > > > > Cheers - > > > Techi > > > _______________________________________________ > > > sqlite-users mailing list > > > sqlite-users@sqlite.org > > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > > > > > > > -------------------------------------------------------------------- > > > -- > > > ---- > > > Gunter Hick > > > Software Engineer > > > Scientific Games International GmbH > > > Klitschgasse 2 - 4, A - 1130 Vienna, Austria FN 157284 a, HG Wien > > > Tel: +43 1 80100 0 > > > E-Mail: h...@scigames.at > > > > > > This e-mail is confidential and may well also be legally privileged. > > > If you have received it in error, you are on notice as to its status > > > and accordingly please notify us immediately by reply e-mail and > > > then delete this message from your system. Please do not copy it or > > > use it for any purposes, or disclose its contents to any person as > > > to do so could be a breach of confidence. Thank you for your > cooperation. > > > _______________________________________________ > > > sqlite-users mailing list > > > sqlite-users@sqlite.org > > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > > > _______________________________________________ > > sqlite-users mailing list > > sqlite-users@sqlite.org > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > > > > ---------------------------------------------------------------------- > > ---- > > Gunter Hick > > Software Engineer > > Scientific Games International GmbH > > Klitschgasse 2 - 4, A - 1130 Vienna, Austria FN 157284 a, HG Wien > > Tel: +43 1 80100 0 > > E-Mail: h...@scigames.at > > > > This e-mail is confidential and may well also be legally privileged. > > If you have received it in error, you are on notice as to its status > > and accordingly please notify us immediately by reply e-mail and then > > delete this message from your system. Please do not copy it or use it > > for any purposes, or disclose its contents to any person as to do so > > could be a breach of confidence. Thank you for your cooperation. > > _______________________________________________ > > sqlite-users mailing list > > sqlite-users@sqlite.org > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > -------------------------------------------------------------------------- > Gunter Hick > Software Engineer > Scientific Games International GmbH > Klitschgasse 2 – 4, A - 1130 Vienna, Austria > FN 157284 a, HG Wien > Tel: +43 1 80100 0 > E-Mail: h...@scigames.at > > This e-mail is confidential and may well also be legally privileged. If > you have received it in error, you are on notice as to its status and > accordingly please notify us immediately by reply e-mail and then delete > this message from your system. Please do not copy it or use it for any > purposes, or disclose its contents to any person as to do so could be a > breach of confidence. Thank you for your cooperation. > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
