Re: [boost] Report from Berlin C++ Standards Committee meeting

From: Andreas Pokorny (andreas.pokorny_at_[hidden])
Date: 2006-04-15 17:15:13

On Sat, Apr 15, 2006 at 10:19:30AM +0100, Reece Dunn <msclrhd_at_[hidden]> wrote:
> Steve Hutton wrote:
> > The idea is that to select all rows, you fetch within a loop.  The
> > vector gets resized to contain the number of rows returned.
> > 
> > const int BATCH_SIZE = 30;
> > std::vector<int> valsOut(BATCH_SIZE);
> > Statement st = (sql.prepare <<  "select value from numbers", 
> > 		                into(valsOut));
> > st.execute();
> > while (st.fetch())
> > {
> >     std::vector<int>::iterator pos;
> >     for(; pos != valsOut.end(); ++pos)
> >     {
> > 	cout << *pos << '\n'; 
> >     }
> > }
> > 
> > http://soci.sourceforge.net/doc/statements.html
> 
> How abouit something like:
> 
> sql::statement query;
> query << "select value from numbers";
> 
> sql::rowset< int > rows(query);
> cout << "found = " << rows.size() << endl;
> 
> std::vector< int > values;
> std::copy( rows.begin(), rows.end(), values );
> 
> Multi-item row searches could use tuple:
> 
> sql::rowset< int, std::wstring, int > rows( query );
> std::tr1::tuple< int, std::wstring, int > value = rows.begin();

Slightly offtopic, but what about something like:

using std::sql::select;
using std::sql::from;

auto query = select >> value >> from >> numbers;
typedef decltype(query)::tuple_type tuple_type;

sql::rowset<tuple_type> rows(query,db);
... 

or maybe a more generic reational syntax... 

Regards
Andreas Pokorny