The object-oriented SQL interface has the same three iteration constructs as the functional interface (see Iteration): a
loop, a mapping function, and an extension to the Common Lisp loop macro. However, in this case, the iteration focus is not a tuple of attributes (that is, a record), but a tuple of instances. For example:
(loop for (jones company) being the tuples in
[select 'person 'organisation
:where [= [slot-value 'person 'surname] "Jones"]]
do (format t "~A ~A ~%"
(slot-value jones 'forename)
(slot-value company 'short-name)))
Note: Instances may denote many database records, and hence the effective iteration focus in this case is a tuple of sets of tuples of attributes.
LispWorks User Guide and Reference Manual - 21 Dec 2011