From 4ece53265203d2fc777cc126db64360acfbf5805 Mon Sep 17 00:00:00 2001
From: 2748109647 <196059414+2748109647@users.noreply.github.com>
Date: Sat, 17 Oct 2026 06:21:41 +0800
Subject: [PATCH] fix: parse PostgreSQL GROUP BY DISTINCT

---
 .../jsqlparser/statement/select/GroupByElement.java | 13 +++++++++++++
 .../net/sf/jsqlparser/parser/JSqlParserCC.jjt       |  1 +
 .../sf/jsqlparser/statement/select/SelectTest.java  |  7 +++++++
 3 files changed, 21 insertions(+)

diff --git a/src/main/java/net/sf/jsqlparser/statement/select/GroupByElement.java b/src/main/java/net/sf/jsqlparser/statement/select/GroupByElement.java
index b0ba784b7..82283e0b4 100644
--- a/src/main/java/net/sf/jsqlparser/statement/select/GroupByElement.java
+++ b/src/main/java/net/sf/jsqlparser/statement/select/GroupByElement.java
@@ -33,11 +33,21 @@ public enum SortDirection {
     private List<ExpressionList<Expression>> groupingSets = new ArrayList<>();
     // postgres rollup is an ExpressionList
     private boolean mysqlWithRollup = false;
+    private boolean distinct = false;
 
     public boolean isUsingBrackets() {
         return groupByExpressions.isUsingBrackets();
     }
 
+    public boolean isDistinct() {
+        return distinct;
+    }
+
+    public GroupByElement setDistinct(boolean distinct) {
+        this.distinct = distinct;
+        return this;
+    }
+
     public <T, S> T accept(GroupByVisitor<T> groupByVisitor, S context) {
         return groupByVisitor.visit(this, context);
     }
@@ -115,6 +125,9 @@ public String toString() {
     public void appendTo(StringBuilder builder, Consumer<ExpressionList<?>> listRenderer,
             Consumer<Expression> expressionRenderer) {
         builder.append("GROUP BY ");
+        if (distinct) {
+            builder.append("DISTINCT ");
+        }
         if (groupByExpressions != null) {
             if (hasGroupBySortDirections()) {
                 appendOrderedExpressions(builder, expressionRenderer);
diff --git a/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt b/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt
index 2210dbe9d..08ba29bfc 100644
--- a/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt
+++ b/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt
@@ -10452,6 +10452,7 @@ GroupByElement GroupByColumnReferences():
 }
 {
     <K_GROUP> <K_BY>
+    [ LOOKAHEAD(<K_DISTINCT>) <K_DISTINCT> { groupBy.setDistinct(true); } ]
     (
         LOOKAHEAD(2) (
             <K_GROUPING> <K_SETS>
diff --git a/src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java b/src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java
index a09ab4be3..045ed7eed 100644
--- a/src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java
+++ b/src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java
@@ -4792,6 +4792,13 @@ public void testGroupingSets3() throws JSQLParserException {
                 "SELECT COL_1 FROM TABLE_1 GROUP BY GROUPING SETS (COL_1, ())");
     }
 
+    @Test
+    public void testGroupingSetsDistinctIssue2785() throws JSQLParserException {
+        PlainSelect select = (PlainSelect) assertSqlCanBeParsedAndDeparsed(
+                "SELECT 1 GROUP BY DISTINCT GROUPING SETS ((1), (1))");
+        assertTrue(select.getGroupBy().isDistinct());
+    }
+
     @Test
     public void testLongQualifiedNamesIssue763() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed(