Common SQL supports a symbolic query syntax across both the functional and object-oriented interface layers. It allows SQL and Common Lisp expressions to be mixed together -- with as much processing as possible done at compile-time. Symbolic SQL expressions are read as square-bracketed lists to distinguish them from Lisp expressions. However, each can be nested within the other to achieve the desired result.
By default, this reader syntax is turned off. To turn it on see Utilities.
LispWorks User Guide and Reference Manual - 21 Dec 2011