fix #451

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changes
 
 * 2.4.next in progress
+  * Address [#451](https://github.com/seancorfield/honeysql/issues/451) by adding a test for it, showing how `:nest` produces the desired result.
   * Address [#447](https://github.com/seancorfield/honeysql/issues/447) by updating GitHub Actions and dependencies.
   * Address [#445](https://github.com/seancorfield/honeysql/issues/445) and [#453](https://github.com/seancorfield/honeysql/issues/453) by adding key/constraint examples to `CREATE TABLE` docs.
 

test/honey/union_test.cljc

@@ -0,0 +1,51 @@
+;; copyright (c) 2023 sean corfield, all rights reserved
+
+(ns honey.union-test
+  (:refer-clojure :exclude [format])
+  (:require [clojure.test :refer [deftest is]]
+            [honey.sql :as sut]))
+
+(deftest issue-451
+  (is (=  [(str "SELECT ids.id AS id"
+                " FROM ((SELECT dimension.human_readable_field_id AS id"
+                " FROM dimension AS dimension"
+                " WHERE (dimension.field_id = ?) AND (dimension.human_readable_field_id IS NOT NULL)"
+                " LIMIT ?)"
+                " UNION"
+                " (SELECT dest.id AS id"
+                " FROM field AS source"
+                " LEFT JOIN table AS table ON source.table_id = table.id"
+                " LEFT JOIN field AS dest ON dest.table_id = table.id"
+                " WHERE (source.id = ?) AND (source.semantic_type IN (?)) AND (dest.semantic_type IN (?))"
+                " LIMIT ?)) AS ids"
+                " LIMIT ?")
+           1
+           1
+           1
+           "type/PK"
+           "type/Name"
+           1
+           1]
+          (-> {:select [[:ids.id :id]]
+               :from   [[{:union
+                          [{:nest
+                            {:select [[:dimension.human_readable_field_id :id]]
+                             :from   [[:dimension :dimension]]
+                             :where  [:and
+                                      [:= :dimension.field_id 1]
+                                      [:not= :dimension.human_readable_field_id nil]]
+                             :limit  1}}
+                           {:nest
+                            {:select    [[:dest.id :id]]
+                             :from      [[:field :source]]
+                             :left-join [[:table :table] [:= :source.table_id :table.id] [:field :dest] [:= :dest.table_id :table.id]]
+                             :where     [:and
+                                         [:= :source.id 1]
+                                         [:in :source.semantic_type #{"type/PK"}]
+                                         [:in :dest.semantic_type #{"type/Name"}]]
+                             :limit     1}}]}
+                         :ids]]
+               :limit  1}
+              (sut/format))))
+
+)