15.14.1 Converting between universal time and DATE or TIMESTAMP

The functions sql:encode-db-standard-timestamp, sql:encode-db-standard-date, sql:decode-to-db-standard-date and sql:decode-to-db-standard-timestamp are now exported and documented.

They convert between Lisp universal time and standard SQL DATE and TIMESTAMP.

15.14.2 Fix for list-attribute-types with PostgreSQL and MySQL

The last element in each of the lists that sql:list-attribute-types returns, the nullable value, was wrong (not matching the documentation) for database types :mysql and :postgresql. It is fixed now to return the values as documented.

15.14.3 Warning re list-attribute-types with Access

When using ODBC to connect to Access database, the nullable value that sql:list-attribute-types returns is not reliable, at least in version 7.1. There seems to be a bug in the driver. Using ODBC with other DBMS works as documented.

15.14.4 SQL [...] syntax for = and <> generates IS NULL when used with nil

The SQL code generated for the SQL syntax [= [field] value] is now FIELD IS NULL if value is nil.

Likewise, [<> [field] value] now generates FIELD IS NOT NULL if value is nil.

In LispWorks 6.1 and earlier versions these generated a comparison with NULL, which SQL defines as always false.