From e148cb97f446d147554c38d087cfd382f193af16 Mon Sep 17 00:00:00 2001
From: Ryan Chae <ryan@chequer.io>
Date: Tue, 25 Jul 2023 18:28:29 +0900
Subject: [PATCH] Fix having clause constraint

---
 Qsi.MySql/Tree/Visitors/ExpressionVisitor.cs | 10 ++++++++++
 Qsi.MySql/Tree/Visitors/TableVisitor.cs      |  5 ++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Qsi.MySql/Tree/Visitors/ExpressionVisitor.cs b/Qsi.MySql/Tree/Visitors/ExpressionVisitor.cs
index 5f380172..fa291308 100644
--- a/Qsi.MySql/Tree/Visitors/ExpressionVisitor.cs
+++ b/Qsi.MySql/Tree/Visitors/ExpressionVisitor.cs
@@ -1585,6 +1585,16 @@ public static QsiLiteralExpressionNode VisitFractionalPrecision(FractionalPrecis
     }
 
     #region Having Clause
+    public static QsiGroupingExpressionNode MakeEmptyQsiGroupingExpressionNode(HavingClauseContext context)
+    {
+        return TreeHelper.Create<QsiGroupingExpressionNode>(n =>
+        {
+            n.Items.AddRange(new List<QsiExpressionNode>(0));
+
+            MySqlTree.PutContextSpan(n, context);
+        });
+    }
+
     public static QsiExpressionNode VisitHavingClause(HavingClauseContext context)
     {
         return VisitExpr(context.expr());
diff --git a/Qsi.MySql/Tree/Visitors/TableVisitor.cs b/Qsi.MySql/Tree/Visitors/TableVisitor.cs
index 81e4884e..5e733739 100644
--- a/Qsi.MySql/Tree/Visitors/TableVisitor.cs
+++ b/Qsi.MySql/Tree/Visitors/TableVisitor.cs
@@ -700,7 +700,10 @@ public static QsiTableNode VisitQuerySpecification(QuerySpecificationContext con
                     node.Grouping.SetValue(ExpressionVisitor.VisitGroupByClause(groupByClause));
                     break;
 
-                case HavingClauseContext havingClause when !node.Grouping.IsEmpty:
+                case HavingClauseContext havingClause:
+                    if (node.Grouping.IsEmpty)
+                        node.Grouping.SetValue(ExpressionVisitor.MakeEmptyQsiGroupingExpressionNode(havingClause));
+
                     node.Grouping.Value.Having.SetValue(ExpressionVisitor.VisitHavingClause(havingClause));
                     break;