Fixes #128 by adding :truncate / truncate

CHANGES.md

@@ -1,6 +1,7 @@
 ## Changes coming in 0.9.7
 
 * Fix #248 by treating alias as "not a subquery" when generating SQL for it. (@seancorfield)
+* Fix #128 by adding `truncate` support.
 * Fix #99 by adding a note to the first use of `select` in the README that column names can be keywords or symbols but not strings.
 
 ## 0.9.6

README.md

@@ -228,6 +228,14 @@ If your database supports it, you can also delete from multiple tables:
     "musical"]
 ```
 
+If you want to delete everything from a table, you can use `truncate`:
+
+```clojure
+(-> (truncate :films)
+    sql/format)
+=> ["TRUNCATE films"]
+```
+
 Queries can be nested:
 
 ```clojure

src/honeysql/format.cljc

@@ -219,6 +219,7 @@
    :update 70
    :delete 75
    :delete-from 80
+   :truncate 85
    :columns 90
    :from 110
    :join 120
@@ -629,6 +630,9 @@
 (defmethod format-clause :delete [[_ tables] _]
   (str "DELETE " (comma-join (map to-sql tables))))
 
+(defmethod format-clause :truncate [[_ table] _]
+  (str "TRUNCATE " (to-sql table)))
+
 (defn cte->sql
   [[cte-name query]]
   (str (binding [*subquery?* false]

src/honeysql/helpers.cljc

@@ -279,6 +279,13 @@
   ([tables] (delete nil tables))
   ([m tables] (build-clause :delete m tables)))
 
+(defmethod build-clause :truncate [_ m table]
+  (assoc m :truncate table))
+
+(defn truncate
+  ([table] (truncate nil table))
+  ([m table] (build-clause :truncate m table)))
+
 (macros/usetime
  (defhelper with [m ctes]
    (assoc m :with ctes)))

test/honeysql/format_test.cljc

@@ -228,6 +228,11 @@
               :where [:= :t1.bar 42]}
              (format :quoting :mysql)))))
 
+(deftest truncate-test
+  (is (= ["TRUNCATE `foo`"]
+         (-> {:truncate :foo}
+             (format :quoting :mysql)))))
+
 (deftest inlined-values-are-stringified-correctly
   (is (= ["SELECT foo, bar, NULL"]
          (format {:select [(honeysql.core/inline "foo")