Hi Tatiana,

On Sun, 8 Jul 2018 21:48:32 +0200
Tatiana Sholokhova <tanja201396@gmail.com> wrote:

> Do you have ideas on how to
> implement tuple comparison and other routines in SQL and guile in a
> convenient and flexible way?

sqlite3 supports row values, so the comparison can be
written like this:

  select * from foo where (a,b,c) = (2,'foo',3);

It even supports NULLs for wildcards, though it's a little more complicated:

  select * from foo where coalesce((a,b,c) = (2,NULL,3), 1) = 1;

The sqlite C interface doesn't support parameter bindings for the entire
row, though, so you'd have to specify 3 values.

This works:

  (sqlite-exec db "select * from foo where (a,b,c) = (" 2 "," "foo" "," 3 ");")

but this doesn't work, unfortunately:

  (sqlite-exec db "select * from foo where (a,b,c) = " '(2 "foo" 3) ";")

See also https://www.sqlite.org/rowvalue.html