From d95361572729672f9fc0484db9df6d62596f5a19 Mon Sep 17 00:00:00 2001
From: Niels van Klaveren <github@kometa.demon.nl>
Date: Tue, 19 Aug 2014 11:11:09 +0200
Subject: [PATCH] Added OVER (PARTITION BY) clause   Supports windowed
 aggregate functions as fields   {:aggregate :%fn.field :over {:partition-by
 [:field]}}

---
 src/honeysql/format.clj  | 14 ++++++++++++--
 src/honeysql/helpers.clj | 23 +++++++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/honeysql/format.clj b/src/honeysql/format.clj
index 004a640..14bc31e 100644
--- a/src/honeysql/format.clj
+++ b/src/honeysql/format.clj
@@ -157,8 +157,8 @@
 (def clause-order
   "Determines the order that clauses will be placed within generated SQL"
   [:select :insert-into :update :delete-from :columns :set :from :join
-   :left-join :right-join :where :group-by :having :order-by :limit :offset
-   :values :query-values])
+   :left-join :right-join :where :aggregate :over :partition-by :group-by
+   :having :order-by :limit :offset :values :query-values])
 
 (def known-clauses (set clause-order))
 
@@ -386,3 +386,13 @@
 
 (defmethod format-clause :delete-from [[_ table] _]
   (str "DELETE FROM " (to-sql table)))
+
+(defmethod format-clause :over [[_ part-clause] _]
+  (str "OVER " (to-sql part-clause)))
+
+(defmethod format-clause :aggregate [[_ aggregate-fn] _]
+  (str (to-sql aggregate-fn)))
+
+(defmethod format-clause :partition-by [[_ fields] _]
+  (str "PARTITION BY "
+       (comma-join (map to-sql fields))))
diff --git a/src/honeysql/helpers.clj b/src/honeysql/helpers.clj
index 91c1ca2..a0333de 100644
--- a/src/honeysql/helpers.clj
+++ b/src/honeysql/helpers.clj
@@ -209,3 +209,26 @@
 (defn delete-from
   ([table] (delete-from nil table))
   ([m table] (build-clause :delete-from m table)))
+
+(defmethod build-clause :over [_ m table]
+  (assoc m :over table))
+
+(defn over
+  ([part-clause] (over nil part-clause))
+  ([m part-clause] (build-clause :over m part-clause)))
+
+(defhelper merge-over [m fields]
+  (update-in m [:over] (partial apply merge) (collify fields)))
+
+(defhelper aggregate [m aggregate-fn]
+  (assoc m :aggregate aggregate-fn))
+
+(defn aggregate
+  ([table] (aggregate nil table))
+  ([m table] (build-clause :aggregate m table)))
+
+(defhelper spartition-by [m fields]
+  (assoc m :partition-by (collify fields)))
+
+(defhelper merge-partition-by [m fields]
+  (update-in m [:partition-by] concat (collify fields)))