[soci-users] Join of two or more databases

[Deane Yang]

Does a query like this work in SOCI:

select trades.price, bonds.coupon from trades, bonds where trades.id =
bonds.id

?

I tried something like this and it didn't seem to work.

[Mateusz Loskot]

Post by Deane Yang
select trades.price, bonds.coupon from trades, bonds where trades.id =
bonds.id

I don't see why it should not work.
One of possible examples how to use SOCI with such query:

session sql(backEnd, connectString);
sql << "create table trades (id integer, p integer)";
sql << "create table bonds (id integer, c integer)";
sql << "insert into trades (id, p) values (1, 100)";
sql << "insert into trades (id, p) values (2, 200)";
sql << "insert into trades (id, p) values (3, 300)";
sql << "insert into bonds (id, c) values (1, 7)";
sql << "insert into bonds (id, c) values (3, 9)";

auto init_fetch = 2U;
std::vector<int> prices(init_fetch);
std::vector<int> coupons(init_fetch);
sql << "select trades.p, bonds.c "
<< "from trades, bonds where trades.id = bonds.id"
, into(prices), into(coupons);

std::transform(prices.cbegin(), prices.cend(), coupons.cbegin(),
std::ostream_iterator<std::string>(std::cout, "\n"),
[] (int p, int c) {
return "price: " + std::to_string(p) +
", coupon: " + std::to_string(c);
});
// price: 100, coupon: 7
// price: 300, coupon: 9


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Best regards,
--
Mateusz Loskot, http://mateusz.loskot.net