Re: [sqlite] How to design this table?
> Simon Slavin writes: > On 9 Oct 2011, at 3:57am, 张一帆 wrote: >> i have some data like "a and b or c ...",there will be a word 'and' >> or 'or' which means the Logical relations between each item. > If you have "a and b or c" does that mean > (a and b) or cOR > a and (b or c)? > How does your software know ? The boolean AND and OR operations are often compared to the usual arithmetics' × and +. Therefore, a AND b OR c is akin to a × b + c, and the precedence rules (borrowed from arithmetics) will make that (a × b) + c. And SQLite, among many others, behaves just like that: $ sqlite3 :memory: 'SELECT 0 AND 1 OR 1' 1 $ sqlite3 :memory: 'SELECT 0 AND (1 OR 1)' 0 $ I guess that it just follows the standard. -- FSF associate member #7257 ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] How to design this table?
张一帆 wrote: > i have some data like "a and b or c ...",there will be a word 'and' or > 'or' which means the Logical relations between each item.So how to design a > table to store the data in best way? Best way to achieve which goals? What operations do you need to perform on said data? -- Igor Tandetnik ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] How to design this table?
> > i have some data like "a and b or c ...",there will be a word 'and' or > > 'or' which means the Logical relations between each item. > If you have "a and b or c" does that mean > (a and b) or c OR > a and (b or c) ? > How does your software know ? > Simon. just a and b or c...,like this.thank you! i am also think about the solution of this case.Do you have any ideas? ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] How to design this table?
On 9 Oct 2011, at 3:57am, 张一帆 wrote: > i have some data like "a and b or c ...",there will be a word 'and' or > 'or' which means the Logical relations between each item. If you have "a and b or c" does that mean (a and b) or cOR a and (b or c)? How does your software know ? Simon. ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users