Output GROUP BY before ORDER BY in ProjectionSelectQuery

ClickHouse outputs GROUP BY before ORDER BY in projection EXPLAIN AST.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kyleconroy

internal/explain/statements.go

@@ -1990,6 +1990,13 @@ func explainProjectionSelectQuery(sb *strings.Builder, q *ast.ProjectionSelectQu
 			Node(sb, col, depth+2)
 		}
 	}
+	// GROUP BY comes before ORDER BY in projection output
+	if len(q.GroupBy) > 0 {
+		fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, len(q.GroupBy))
+		for _, expr := range q.GroupBy {
+			Node(sb, expr, depth+2)
+		}
+	}
 	if len(q.OrderBy) > 0 {
 		if len(q.OrderBy) == 1 {
 			// Single column: just output as Identifier
@@ -2003,12 +2010,6 @@ func explainProjectionSelectQuery(sb *strings.Builder, q *ast.ProjectionSelectQu
 			}
 		}
 	}
-	if len(q.GroupBy) > 0 {
-		fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, len(q.GroupBy))
-		for _, expr := range q.GroupBy {
-			Node(sb, expr, depth+2)
-		}
-	}
 }
 
 func explainStatisticsCommand(sb *strings.Builder, cmd *ast.AlterCommand, indent string, depth int) {

parser/testdata/01710_projection_group_by_order_by/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt3": true
-  }
-}
+{}