Db-Select-Single-Column names a function, with lambda list (TABLE COLUMN &REST COLUMNS+VALUES):
Select COLUMN from TABLE where columns = values as in plist COLUMNS+VALUES.
Expects to find only one row and return the one column value as an atom.
Signal an error if more rows are returned.
Signals NOT-FOUND if none are found.
Uses MemCacheD when available.
Defined in file src/db/maria.lisp.