No data results hides subsequent result sets. #60
Description
From @aquasync on December 30, 2014 0:48
I'm using nanodbc to run a chunk of sql containing multiple statements (dml/ddl along with selects), and iterating through the results with something like the following:
nanodbc::connection db("...");
nanodbc::result res = execute(db, sql);
do {
if (bool(res) && res.columns() > 0) {
// process resultset
}
} while (bool(res) && res.next_result());
I ran into the situation where queries which return no data return a default-constructed result object, as the SQL_NO_DATA path in execute/execute_direct is taken. This causes it to have no underlying result_impl or reference to the statement, so you are unable to advance to subsequent result sets. Adding a preceding dummy query seems to fix this.
For example, in "select top 0 1 as a into #temp; select 2 as b", data from the latter select is not reachable, but prepending "select 1 as a into #dummy; " returns a valid result object allowing you to iterate to the final result set.
Commenting out the above-mentioned SQL_NO_DATA path in both execute & execute_direct fixes this for me by returning a valid result object always. Could this be deleted upstream or is it needed in some other situtation?
Copied from original issue: lexicalunit/nanodbc#33