This command provides a fuzzy search method, alternative to
Synonyms and Ispell methods. It allows to specify a SQL
query which will be executed to generate word forms or synonyms
from the database. The query must return exactly one column with
individual word form or synonym on a separate row. The query is
sent to the database specified in DBAddr command. If the case of
multiple DBAddr commands, only the first one is used for word forms
generating. The SQL query is executed for every word typed by the user,
with the "$1" macro replaced to the word.