sql_select.cc:

  Fixed bug #9681.
  The bug happened with queries using derived tables specified by
  a SELECT with ROLLUP, such as:
  SELECT * FROM (SELECT a, SUM(a) FROM t1 GROUP BY a WITH ROLLUP) t2,
  if column a of table t1 is declared as NOT NULL.
  This was to the fact that the first column of the temporary table
  created to contain the derived table erroneously inherited the NOT NULL
  attribute from column a.
olap.result, olap.test:
  Added a test case for bug #9681.

mysql-test/r/olap.result

@@ -392,3 +392,16 @@ SELECT SQL_CALC_FOUND_ROWS a, SUM(b) FROM t1 GROUP BY a WITH ROLLUP LIMIT 1;
 a	SUM(b)
 1	4
 DROP TABLE t1;
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP;
+a	m
+1	1
+2	2
+NULL	3
+SELECT * FROM ( SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP ) t2;
+a	m
+1	1
+2	2
+NULL	3
+DROP TABLE t1;

mysql-test/t/olap.test

@@ -171,3 +171,16 @@ SELECT a, SUM(b) FROM t1 GROUP BY a WITH ROLLUP LIMIT 1;
 SELECT SQL_CALC_FOUND_ROWS a, SUM(b) FROM t1 GROUP BY a WITH ROLLUP LIMIT 1;
 
 DROP TABLE t1;
+
+#
+# Tests for bug #9681: ROLLUP in subquery for derived table wiht 
+#                      a group by field declared as NOT NULL
+#
+
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+
+SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP;
+SELECT * FROM ( SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP ) t2;
+
+DROP TABLE t1;

sql/sql_select.cc

@@ -4779,7 +4779,7 @@ static Field* create_tmp_field_from_field(THD *thd, Field* org_field,
       item->result_field= new_field;
     else
       new_field->field_name= name;
-    if (org_field->maybe_null())
+    if (org_field->maybe_null() || (item && item->maybe_null))
       new_field->flags&= ~NOT_NULL_FLAG;	// Because of outer join
     if (org_field->type() == FIELD_TYPE_VAR_STRING)
       table->db_create_options|= HA_OPTION_PACK_RECORD;
@@ -9192,7 +9192,19 @@ bool JOIN::rollup_init()
     for (j=0 ; j < fields_list.elements ; j++)
       rollup.fields[i].push_back(rollup.null_items[i]);
   }
+  List_iterator_fast<Item> it(fields_list);
+  Item *item;
+  while ((item= it++))
+  {
+    ORDER *group_tmp;
+    for (group_tmp= group_list; group_tmp; group_tmp= group_tmp->next)
+    {
+      if (*group_tmp->item == item)
+        item->maybe_null= 1;
+    }
+  }
   return 0;
+
 }