- Support for comparing composite value members in queries

- Support for out parameters in SQL Server stored procedures [mssql]

  Seems like re-using the by-ref machinery is the most sensible way.
  See also paper notes.

- Support for Table-Valued Parameters in SQL Server [mssql]

  See paper notes.

- Implement and document how to call stored procedures in each DB

  Also some DBs distinguish between procedures and functions. Need
  to figure out and show that as well. And test. See MySQL as an
  example.

  Add test for MySQL and all the other databases (have some code
  saved).

- Add the call() function to call stored procedures [c++11]

  Will have a variadic number of arguments so one doesn't have to
  keep adding ",".

  Also the ability to provide a stored procedure name first.

? Support for sub-queries in the query() call.

  Will probably also need the generalized data members (for SELECT-
  list).