From a51cfe5a2ea10464961d26433285750c97598d34 Mon Sep 17 00:00:00 2001
From: Sean Corfield <sean@corfield.org>
Date: Sat, 12 Jun 2021 18:15:59 -0700
Subject: [PATCH] Fixes #328 by adding :distinct special syntax

---
 CHANGELOG.md          | 1 +
 doc/special-syntax.md | 9 +++++++++
 src/honey/sql.cljc    | 4 ++++
 3 files changed, 14 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68c9a7d..0df5758 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changes
 
 * 2.0.next in progress
+  * Fix #328 by adding `:distinct` as special syntax, affecting an expression.
   * Support PostgreSQL's `&&` array operator.
   * Clarify how to `SELECT` a function expression (in **Getting Started**).
 
diff --git a/doc/special-syntax.md b/doc/special-syntax.md
index 04ab495..97b2681 100644
--- a/doc/special-syntax.md
+++ b/doc/special-syntax.md
@@ -60,6 +60,15 @@ expression (comma-separated, wrapped in parentheses):
 ;;=> ["(a, b, ?, x + ?)" "red" 1]
 ```
 
+## distinct
+
+Accepts a single expression and prefixes it with `DISTINCT `:
+
+```clojure
+(sql/format {:select [ [[:count [:distinct :status]] :n] ] :from :table})
+;;=> ["SELECT COUNT(DISTINCT status) AS n FROM table"]
+```
+
 ## entity
 
 Accepts a single keyword or symbol argument and produces a
diff --git a/src/honey/sql.cljc b/src/honey/sql.cljc
index 73fb85c..3684085 100644
--- a/src/honey/sql.cljc
+++ b/src/honey/sql.cljc
@@ -1074,6 +1074,10 @@
     (fn [_ [& args]]
       (let [[sqls params] (format-expr-list args)]
         (into [(str "(" (str/join ", " sqls) ")")] params)))
+    :distinct
+    (fn [_ [x]]
+      (let [[sql & params] (format-expr x {:nested true})]
+        (into [(str "DISTINCT " sql)] params)))
     :escape
     (fn [_ [pattern escape-chars]]
       (let [[sql-p & params-p] (format-expr pattern)