Merge mysql.com:/home/hf/work/mrg/mysql-5.0-opt

into  mysql.com:/home/hf/work/mrg/mysql-5.1-opt

mysql-test/r/union.result

@@ -1426,4 +1426,15 @@ select _utf8'12' union select _latin1'12345';
 12
 12
 12345
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (3),(1),(2),(4),(1);
+SELECT a FROM (SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a) AS test;
+a
+1
+2
+3
+4
+SELECT a FROM (SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY c) AS test;
+ERROR 42S22: Unknown column 'c' in 'order clause'
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/union.test

@@ -900,4 +900,17 @@ drop table t1, t2;
 #
 select _utf8'12' union select _latin1'12345';
 
+#
+# Bug #26661: UNION with ORDER BY undefined column in FROM list
+#
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (3),(1),(2),(4),(1);
+
+SELECT a FROM (SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a) AS test;
+--error 1054 
+SELECT a FROM (SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY c) AS test;
+
+DROP TABLE t1;
+
 --echo End of 5.0 tests

sql/item.cc

@@ -3475,7 +3475,12 @@ Item_field::fix_outer_field(THD *thd, Field **from_field, Item **reference)
   */
   Name_resolution_context *last_checked_context= context;
   Item **ref= (Item **) not_found_item;
-  Name_resolution_context *outer_context= context->outer_context;
+  SELECT_LEX *current_sel= (SELECT_LEX *) thd->lex->current_select;
+  Name_resolution_context *outer_context= 0;
+  /* Currently derived tables cannot be correlated */
+  if (current_sel->master_unit()->first_select()->linkage !=
+      DERIVED_TABLE_TYPE)
+    outer_context= context->outer_context;
   for (;
        outer_context;
        outer_context= outer_context->outer_context)