[odb-users] Constructing native queries without a where clause fails (sqlite)

[Boris Kolpackov]

Hi Feisal,

Feisal Ahmad <feisal.ahmad at ps-tech.com> writes:

> 		sq_query selectAll;
> 		result r = m_db->query<T>(selectAll + " LIMIT " +
> sq_query::_val(maxResults) + " OFFSET " + sq_query::_val(first));

We are not recognizing LIMIT and OFFSET as special prefixes yet
(on the TODO list though) so what you can do for now is this:

sq_query selectAll (true);
result r = m_db->query<T>(selectAll + " LIMIT " + 
  sq_query::_val(maxResults) + " OFFSET " + sq_query::_val(first));

You also don't have to add spaces around LIMIT and OFFSET, ODB will
do it for you. So here is how I would write this query:

result r = m_db->query<T>(sq_query(true) + 
                          "LIMIT" + sq_query::_val(maxResults) + 
                          "OFFSET" + sq_query::_val(first));


> Also, any help on converting the constructed query to a string for
> debugging would be very welcome.

You can get the WHERE clause (and the rest) using the clause()
function:

sq_query q (sq_query(true) + 
            "LIMIT" + sq_query::_val(maxResults) + 
            "OFFSET" + sq_query::_val(first));

cerr << q.clause () << endl;

If you want to see the whole statement, then statement tracing
is probably the most convenient way:

t.trace (odb::stderr_tracer);

Boris