fixes #551 by supporting multiple window clauses

Signed-off-by: Sean Corfield <sean@corfield.org>

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changes
 
 * 2.6.next in progress
+  * Fix [#551](https://github.com/seancorfield/honeysql/issues/551) by supporting multiple `WINDOW` clauses.
   * Fix [#549](https://github.com/seancorfield/honeysql/issues/549) by using `:bb` conditionals to support Babashka (and still support Clojure 1.9.0), and add testing against Babashka so it is fully-supported as a target via PR [#550](https://github.com/seancorfield/honeysql/pull/550) [@borkdude](https://github.com/borkdude)
   * Address [#532](https://github.com/seancorfield/honeysql/issues/532) by adding support for `EXCLUDE` and `RENAME` and starting to write tests for XTDB compatibility.
 

doc/clause-reference.md

@@ -1090,7 +1090,7 @@ but is rendered into the SQL later in precedence order.
 
 ## window, partition-by (and over)
 
-`:window` accepts a pair of SQL entity (the window name)
+`:window` accept alternating pairs of SQL entity (the window name)
 and the window "function" as a SQL clause (a hash map).
 
 `:partition-by` accepts the same arguments as `:select` above
@@ -1116,6 +1116,25 @@ SELECT id, AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) A
 FROM employee
 WINDOW w AS (PARTITION BY department)
 "]
+;; multiple windows:
+user=> (sql/format {:select [:id
+                             [[:over
+                               [[:avg :salary]
+                                {:partition-by [:department]
+                                 :order-by [:designation]}
+                                :Average]
+                               [[:max :salary]
+                                :w
+                                :MaxSalary]]]]
+                    :from [:employee]
+                    :window [:w {:partition-by [:department]}
+                             :x {:partition-by [:salary]}]}
+                    {:pretty true})
+["
+SELECT id, AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) AS Average, MAX(salary) OVER w AS MaxSalary
+FROM employee
+WINDOW w AS (PARTITION BY department), x AS (PARTITION BY salary)
+"]
 ;; easier to write with helpers (and easier to read!):
 user=> (sql/format (-> (select :id
                                (over [[:avg :salary] (-> (partition-by :department) (order-by :designation)) :Average]
@@ -1128,6 +1147,18 @@ SELECT id, AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) A
 FROM employee
 WINDOW w AS (PARTITION BY department)
 "]
+;; multiple window clauses:
+user=> (sql/format (-> (select :id
+                               (over [[:avg :salary] (-> (partition-by :department) (order-by :designation)) :Average]
+                                     [[:max :salary] :w :MaxSalary]))
+                       (from :employee)
+                       (window :w (partition-by :department))
+                       (window :x (partition-by :salary)))                   {:pretty true})
+["
+SELECT id, AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) AS Average, MAX(salary) OVER w AS MaxSalary
+FROM employee
+WINDOW w AS (PARTITION BY department), x AS (PARTITION BY salary)
+"]
 ```
 
 The window function in the `:over` expression may be `{}` or `nil`:

src/honey/sql.cljc

@@ -953,6 +953,9 @@
 (defn- format-selector [k xs]
   (format-selects k [xs]))
 
+(defn- format-window [k xs]
+  (format-selects k (into [] (partition-all 2 xs))))
+
 (declare columns-from-values)
 
 (defn- format-insert [k table]
@@ -1643,7 +1646,7 @@
          :where           #'format-on-expr
          :group-by        #'format-group-by
          :having          #'format-on-expr
-         :window          #'format-selector
+         :window          #'format-window
          :partition-by    #'format-selects
          :order-by        #'format-order-by
          :limit           #'format-on-expr

test/honey/sql/helpers_test.cljc

@@ -533,6 +533,33 @@
                " MAX(salary) OVER w AS MaxSalary"
                " FROM employee"
                " WINDOW w AS (PARTITION BY department)")]))
+  ;; multiple window tests
+  (is (= (-> (select :id
+                     (over [[:avg :salary] (-> (partition-by :department) (order-by :designation)) :Average]
+                           [[:max :salary] :w :MaxSalary]))
+             (from :employee)
+             (window :w (partition-by :department))
+             (window :x (partition-by :salary))
+             sql/format)
+         [(str "SELECT id,"
+               " AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) AS Average,"
+               " MAX(salary) OVER w AS MaxSalary"
+               " FROM employee"
+               " WINDOW w AS (PARTITION BY department)"
+               ", x AS (PARTITION BY salary)")]))
+  (is (= (-> (select :id
+                     (over [[:avg :salary] (-> (partition-by :department) (order-by :designation)) :Average]
+                           [[:max :salary] :w :MaxSalary]))
+             (from :employee)
+             (window :w (partition-by :department)
+                     :x (partition-by :salary))
+             sql/format)
+         [(str "SELECT id,"
+               " AVG(salary) OVER (PARTITION BY department ORDER BY designation ASC) AS Average,"
+               " MAX(salary) OVER w AS MaxSalary"
+               " FROM employee"
+               " WINDOW w AS (PARTITION BY department)"
+               ", x AS (PARTITION BY salary)")]))
   ;; test nil / empty window function clause:
   (is (= (-> (select :id
                      (over [[:avg :salary] {} :Average]