Postgresql Functions
Postgresql functions are typically inserted into s-sql in their own form prefaced with : and their parameters are generally single quoted. Here are a few simple examples.
:avg
(froundn (query (:select (:avg 'latitude)
:from 'countries)
:single)
4)
18.4209
:max
(query (:select (:max 'latitude) :from 'countries) :single)
72
:min
(query (:select (:min 'latitude) :from 'countries) :single)
-1029/20
:random
(query (:limit (:order-by (:select 'id 'name :from 'countries)
(:random))
5))
((54 "Israel") (62 "South Africa") (195 "Aruba") (79 "Costa Rica")
(31 "OECD"))
:string_agg
String_agg returns a string containging the values returned, separated by a delimiter. In the following example, we are searching for the name of all the regions in the regions table and we want it all returned as a single string with a delimiting comma.
(query (:select (:string_agg 'name ",") :from 'regions))
(("Central America,Middle East,North America,South America,Central Asia,Pacific,Caribbean,Eastern Europe,Western Europe,EMEA,APAC,LATAM,Emerging,US,Canada,Africa,All,Asia,Eastern Africa,Middle Africa,Northern Africa,Southern Africa,Western Africa,Oceania,Northern Europe,Southern Europe,Eastern Asia,South Central Asia,South East Asia"))
:version
(query (:select (:version)))
(("PostgreSQL 9.2 on x86_64-pc-linux-gnu, compiled by GCC x86_64"))
(defun table-size (table-name)
"Return the size of a postgresql table in k or m. Table-name can be either a
string or quoted."
(when (symbolp table-name)
(setf table-name (string-downcase (write-to-string table-name))))
(query (:select (:pg_size_pretty (:pg_total_relation_size'$1)))
:single
table-name))
(table-size 'countries)
"88 kB"