add fix for 9807

Author: elianddb

enginetest/queries/join_queries.go

@@ -792,6 +792,22 @@ on w = 0;`,
 }
 
 var JoinScriptTests = []ScriptTest{
+	{
+		// https://github.com/dolthub/dolt/issues/9807
+		Name: "FULL OUTER JOIN fails with empty subquery",
+		SetUpScript: []string{
+			"CREATE TABLE t(c BOOLEAN);",
+			"INSERT INTO t VALUES (FALSE);",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query: "SELECT * FROM ( SELECT c FROM t WHERE c ) sub1 FULL OUTER JOIN ( SELECT 1 AS c ) sub2 ON 1=1;",
+				Expected: []sql.Row{
+					{nil, 1},
+				},
+			},
+		},
+	},
 	{
 		Name:        "Simple join query",
 		SetUpScript: []string{},

sql/rowexec/join_iters.go

@@ -487,6 +487,10 @@ func (i *fullJoinIter) Next(ctx *sql.Context) (sql.Row, error) {
 			}
 			i.r = nil
 			i.leftRow = nil
+			continue
+		}
+		if err != nil {
+			return nil, err
 		}
 
 		row := i.buildRow(i.leftRow, rightRow)
@@ -512,7 +516,7 @@ func (i *fullJoinIter) Next(ctx *sql.Context) (sql.Row, error) {
 
 	for {
 		if i.r == nil {
-			iter, err := i.b.Build(ctx, i.rp, i.leftRow)
+			iter, err := i.b.Build(ctx, i.rp, i.parentRow)
 			if err != nil {
 				return nil, err
 			}