library(odbc):
null. Please note: this is an
incompatible change for string parameters. When passing string
parameters to odbc_query_execute_sql/[3,5] using atoms, the atom
null used to be treated as the four character string consisting
of the characters n, u, l and l but it is now
treated as a SQL “null” value. A workaround is to always pass strings
as lists of character codes (which also works in older versions of
SICStus) or as a list of atoms (which only works in SICStus 4.2.2 and
later).