Thanks Richard. I can’t claim to fully understand the part about the app calling sqlit3_column_text but I’m reassured that leaving the arithmetic to sqlite is the way to go.
From: Richard Hipp<mailto:d...@sqlite.org> Sent: 29 May 2017 14:52 To: SQLite mailing list<mailto:sqlite-users@mailinglists.sqlite.org> Subject: Re: [sqlite] Does prepare do arithmetic? On 5/29/17, x <tam118...@hotmail.com> wrote: > Thanks Clemens, that clears that up. > > I’m still left wondering though why it calculates 2+2 every step in > > ‘select 2+2 from Tbl;’ > All result values must be recomputed on every step because the application can change the value by (for example) calling sqlite3_column_text and thus causing the integer result to be converted into a string result. The result needs to be reset back to an integer for the next row. It is true that SQLite could compute 2+2 and store the result then copy the result into the result register for each result row, but doing the copy is not measurably faster than simply redoing the 2+2 computation. You will notice that in a more complex computation like: SELECT 2*15-5+11/5<<3*1 FROM tbl That the "2*15-5+11/5" and "3*1" subexpressions are computed just once, and only the final "<<" operator is repeated for each row. -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
