Jeff Garland wrote:
Nicola Musatti wrote:
Hallo, a few months ago there was a discussion on how a database interface library would be a welcome addition to TR2 and the SOCI developers suggested that SOCI could be a valid candidate for that role (http://article.gmane.org/gmane.comp.lib.boost.devel/140816). They also mentioned their intention to make SOCI ready for submission to Boost.
Was any progress made on this issue? Is there any interest in reopening the discussion on such a library, SOCI submission notwithstanding?
I'm not sure what there is to discuss. It didn't happen :-( And TR2 submission time is over. I still want to see SOCI or the equivalent in Boost, but the authors have to bring it forward. Last I knew they were waiting to have an ODBC driver first. I didn't see the need for that, but they thought it was essential...
Missing the TR2 deadline was unfortunate, but probably putting together a valid proposal deserved more time than was available, even with such an impressive starting point such as SOCI. Lately I've been trying to put together a few ideas on how I think such a library should look like and I'd be happy to discuss them with anybody who is interested. To get the ball rolling, here is an example of how a program using my hypothetical Boost.Dbi (for DataBase Interface) library might look like: #include <iostream> #include <ostream> #include <boost/optional.hpp> #include <boost/none.hpp> #include <boost/dbi.hpp> int main() { try { // Connect to a database, specifying the underlying technology. Unless // specific SQL syntax is used, this should be the only place where the // actual DBMS product / technology is evident boost::dbi::connection conn("ODBC"); conn.connect("PVAL", "dba", "sql"); // Execute a couple of simple queries boost::dbi::statement st(conn); try { st.exec("drop table t"); conn.commit(); } catch ( boost::dbi::error & e ) { std::cerr << e.what() << '\n'; } st.exec("create table t ( a int, b varchar(10), c double, " "d int )"); // Execute a parameterized query long a; std::string b; boost::optional<double> c; // a value that may be null boost::dbi::null_value<long> d; // a value that is always null // prepare the statement and bind input parameters, so as to // be able to execute it in a loop with different values st.prepare("insert into t ( a, b, c, d ) values ( ?, ?, ?, ? )", a, b, c, d); char * nums[] = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; for ( a = 0; a < 10; ++a ) { b = nums[a]; if ( a % 2 ) c = a * 1.1; else c = boost::none; st.exec(); } conn.commit(); // Execute a query that returns a result set st.exec("select * from t"); boost::dbi::result_set rs(st); // Explore the structure of the result set std::cout << "No. of columns: " << rs.column_count() << '\n'; for ( int i = 0; i < rs.column_count(); ++i ) { std::cout << rs[i].name() << "\t " << rs[i].type().name() << '(' << rs[i].size() << ", " << rs[i].precision() << ')'; if ( rs[i].nullable() ) std::cout << "\t null"; std::cout << '\n'; } // Print the actual results std::cout << "\nRows:\n"; for ( boost::dbi::result_set::iterator i = rs.begin(); i != rs.end(); ++i ) { boost::dbi::row const & r = *i; // Columns may be accessed by position... std::cout << r[0].as<long>() << "\t "; // ...or by name std::cout << r["b"].as<std::string>() << "\t "; boost::optional<double> c = r[2].as<boost::optional<double> >(); if ( ! c ) std::cout << "(null)\t "; else std::cout << *c << "\t "; boost::optional<long> d = r["d"].as<boost::optional<long> >(); if ( ! d ) std::cout << "(null)\n"; else std::cout << *d << '\n'; } conn.disconnect(); } catch ( boost::dbi::error & e ) { std::cerr << e.what() << '\n'; std::cout << "Failure!\n"; return 1; } std::cout << "Success!\n"; } Cheers, Nicola Musatti