Add union/intersection to the dsl

1 files changed, 21 insertions, 17 deletions

diff --git a/src/clojure_sql/compiler.clj b/src/clojure_sql/compiler.clj
index 6b3ec4a..d0b1206 100644
--- a/src/clojure_sql/compiler.clj
+++ b/src/clojure_sql/compiler.clj
@@ -223,24 +223,28 @@
                (if drop
                  (str " OFFSET " drop)))))
 
+(def ^:private set-operations {:union "UNION", :intersect "INTERSECT"})
+
 (defmulti compile-query (fn [db _] db) :default :postgres)
-(defmethod compile-query :postgres [db {:keys [tables fields joins where sort group having union take drop]}]
-  (if union
-    (->> union
-         (map (partial compile-query db))
-         (apply sequence)
-         ((p-lift string/join " UNION ")))
-    ($str (return "SELECT ")
-          (compile-fields db fields)
-          (if tables
-            ($str (return " FROM ")
-                  (compile-tables db joins tables))
-            ($str ""))
-          (compile-where db where)
-          (compile-group db group)
-          (compile-having db having)
-          (compile-sort db sort)
-          (compile-limit db take drop))))
+(defmethod compile-query :postgres [db {:keys [tables fields joins where sort group having take drop set-operation queries]}]
+  (or (if set-operation
+        (let [op-str (str ") " (get set-operations set-operation) " (")]
+          (->> queries
+               (map (partial compile-query db))
+               (apply sequence)
+               ((p-lift string/join op-str))
+               $add-parentheses)))
+      ($str (return "SELECT ")
+            (compile-fields db fields)
+            (if tables
+              ($str (return " FROM ")
+                    (compile-tables db joins tables))
+              ($str ""))
+            (compile-where db where)
+            (compile-group db group)
+            (compile-having db having)
+            (compile-sort db sort)
+            (compile-limit db take drop))))