cl-rdbms abstracts away differences between various SQL databases and provides an advanced compiler for its sexp SQL syntax. It does not try to support object-relational mapping, see cl-perec for that. It also has a cleaner API than some of the other SQL libraries, although YMMV.
darcs get --partial http://common-lisp.net/project/postmodern/darcs/postmodernor you can get the branch we use:
darcs get --partial http://common-lisp.net/project/cl-dwim/darcs/postmodernAt the time of writing there are two patches that are not yet in the official: it uses local-time for time related datatypes and it's using ironclad for generating the hash for the connection.
You can browse the cl-rdbms darcs repository or get the tree with
darcs get --partial http://common-lisp.net/project/cl-rdbms/darcs/cl-rdbms
Public Domain / BSD