diff options
| -rw-r--r-- | src/clojure_sql/compiler.clj | 38 | ||||
| -rw-r--r-- | src/clojure_sql/dsl.clj | 24 |
2 files changed, 43 insertions, 19 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)))) diff --git a/src/clojure_sql/dsl.clj b/src/clojure_sql/dsl.clj index 6ba81bc..0a05763 100644 --- a/src/clojure_sql/dsl.clj +++ b/src/clojure_sql/dsl.clj @@ -177,7 +177,8 @@ (and (nil? (:group query)) (nil? (:having query)) (nil? (:take query)) - (nil? (:drop query)))) + (nil? (:drop query)) + (nil? (:set-operation query)))) (defn ^:private convert-to-subquery [query] (-> (table query) @@ -195,7 +196,7 @@ (def ^:private valid-join-type? (comp boolean #{:cross :inner :outer :full-outer})) (defn join - "Join two queries into one query The fields of the resultant query + "Join two queries into one query. The fields of the resultant query will be the union of the argument queries. If `type` is not provided then the join type will be automatically @@ -376,3 +377,22 @@ (if-let [old-drop (:drop query)] (assoc query :drop (+ old-drop n)) (assoc query :drop n)))) + +(defn ^:private union-compatible? [& queries] + (apply = (map (comp set keys :fields) queries))) + +(defn union + "Combine the results of two queries" + [& queries] + (assert (apply union-compatible? queries) "Unioned queries must expose the same fields.") + (assoc (q/->Query) + :set-operation :union + :queries queries)) + +(defn intersection + "Take the common rows in two queries" + [& queries] + (assert (apply union-compatible? queries) "Unioned queries must expose the same fields.") + (assoc (q/->Query) + :set-operation :intersect + :queries queries)) |