sql_select.cc:

  Fixed bug #11412.
  Reversed the patch of cs 1.1934 for the function 
  create_tmp_table. Modified the function to support
  tem_ref objects created for view fields.
item_buff.cc:
  Fixed bug #11412.
  Modified implementation of new_Cached_item to support
  cacheing of view fields.
item.h:
  Fixed bug #11412.
  Changed implementation of Item_ref::get_tmp_table_field and
  added Item_ref::get_tmp_table_item to support Item_ref objects
  created for view fields.
view.test, view.result:
  Added a test case for bug #11412.

mysql-test/r/view.result

@@ -2024,3 +2024,26 @@ f1	sb
 2005-01-01 12:00:00	2005-01-01 10:58:59
 drop view v1;
 drop table t1;
+CREATE TABLE t1 (
+aid int PRIMARY KEY,
+fn varchar(20) NOT NULL,
+ln varchar(20) NOT NULL
+);
+CREATE TABLE t2 (
+aid int NOT NULL,
+pid int NOT NULL
+);
+INSERT INTO t1 VALUES(1,'a','b'), (2,'c','d');
+INSERT INTO t2 values (1,1), (2,1), (2,2);
+CREATE VIEW v1 AS SELECT t1.*,t2.pid FROM t1,t2 WHERE t1.aid = t2.aid;
+SELECT pid,GROUP_CONCAT(CONCAT(fn,' ',ln) ORDER BY 1) FROM t1,t2 
+WHERE t1.aid = t2.aid GROUP BY pid;
+pid	GROUP_CONCAT(CONCAT(fn,' ',ln) ORDER BY 1)
+1	a b,c d
+2	c d
+SELECT pid,GROUP_CONCAT(CONCAT(fn,' ',ln) ORDER BY 1) FROM v1 GROUP BY pid;
+pid	GROUP_CONCAT(CONCAT(fn,' ',ln) ORDER BY 1)
+1	a b,c d
+2	c d
+DROP VIEW v1;
+DROP TABLE t1,t2;

mysql-test/t/view.test

@@ -1862,4 +1862,28 @@ insert into t1 values('2005.01.01 12:0:0');
 create view v1 as select f1, subtime(f1, '1:1:1') as sb from t1;
 select * from v1;
 drop view v1;
-drop table t1; 
+drop table t1;
+
+#
+# Test for bug #11412: query over a multitable view with GROUP_CONCAT
+#
+CREATE TABLE t1 (
+  aid int PRIMARY KEY,
+  fn varchar(20) NOT NULL,
+  ln varchar(20) NOT NULL
+);
+CREATE TABLE t2 (
+  aid int NOT NULL,
+  pid int NOT NULL
+);
+INSERT INTO t1 VALUES(1,'a','b'), (2,'c','d');
+INSERT INTO t2 values (1,1), (2,1), (2,2);
+
+CREATE VIEW v1 AS SELECT t1.*,t2.pid FROM t1,t2 WHERE t1.aid = t2.aid;
+
+SELECT pid,GROUP_CONCAT(CONCAT(fn,' ',ln) ORDER BY 1) FROM t1,t2 
+  WHERE t1.aid = t2.aid GROUP BY pid;
+SELECT pid,GROUP_CONCAT(CONCAT(fn,' ',ln) ORDER BY 1) FROM v1 GROUP BY pid;
+
+DROP VIEW v1;
+DROP TABLE t1,t2;

sql/item.h

@@ -1464,7 +1464,10 @@ public:
   void save_org_in_field(Field *field)	{ (*ref)->save_org_in_field(field); }
   enum Item_result result_type () const { return (*ref)->result_type(); }
   enum_field_types field_type() const   { return (*ref)->field_type(); }
-  Field *get_tmp_table_field() { return result_field; }
+  Field *get_tmp_table_field()
+  { return result_field ? result_field : (*ref)->get_tmp_table_field(); }
+  Item *get_tmp_table_item(THD *thd)
+  { return (*ref)->get_tmp_table_item(thd); }
   table_map used_tables() const		
   { 
     return depended_from ? OUTER_REF_TABLE_BIT : (*ref)->used_tables(); 
@@ -1702,7 +1705,7 @@ class Cached_item_field :public Cached_item
 public:
   Cached_item_field(Item_field *item)
   {
-    field=item->field;
+    field= item->field;
     buff= (char*) sql_calloc(length=field->pack_length());
   }
   bool cmp(void);

sql/item_buff.cc

@@ -25,9 +25,9 @@
 
 Cached_item *new_Cached_item(THD *thd, Item *item)
 {
-  if (item->type() == Item::FIELD_ITEM &&
-      !(((Item_field *) item)->field->flags & BLOB_FLAG))
-    return new Cached_item_field((Item_field *) item);
+  if (item->real_item()->type() == Item::FIELD_ITEM &&
+      !(((Item_field *) (item->real_item()))->field->flags & BLOB_FLAG))
+    return new Cached_item_field((Item_field *) (item->real_item()));
   switch (item->result_type()) {
   case STRING_RESULT:
     return new Cached_item_str(thd, (Item_field *) item);

sql/sql_select.cc

@@ -8026,6 +8026,12 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
                         bool table_cant_handle_bit_fields,
                         uint convert_blob_length)
 {
+  Item *org_item= item;
+  if (item->real_item()->type() == Item::FIELD_ITEM)
+  {
+    item= item->real_item();
+    type= item->type();
+  }
   switch (type) {
   case Item::SUM_FUNC_ITEM:
   {
@@ -8038,30 +8044,22 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
   case Item::FIELD_ITEM:
   case Item::DEFAULT_VALUE_ITEM:
   {
-    Item_field *field= (Item_field*) item;
-    if (table_cant_handle_bit_fields && field->field->type() == FIELD_TYPE_BIT)
-      return create_tmp_field_from_item(thd, item, table, copy_func,
-                                        modify_item, convert_blob_length);
-    return create_tmp_field_from_field(thd, (*from_field= field->field),
-                                       item->name, table,
-                                       modify_item ? (Item_field*) item : NULL,
-                                       convert_blob_length);
-  }
-  case Item::REF_ITEM:
-  {
-    Item *tmp_item;
-    if ((tmp_item= item->real_item())->type() == Item::FIELD_ITEM)
+    if (org_item->type() != Item::REF_ITEM ||
+        !((Item_ref *)org_item)->depended_from)
     {
-      Item_field *field= (Item_field*) tmp_item;
-      Field *new_field= create_tmp_field_from_field(thd, 
-                               (*from_field= field->field),
-                               item->name, table,
-                               NULL,
-                               convert_blob_length);
-      if (modify_item)
-        item->set_result_field(new_field);
-      return new_field;
+      Item_field *field= (Item_field*) item;
+      if (table_cant_handle_bit_fields && 
+          field->field->type() == FIELD_TYPE_BIT)
+        return create_tmp_field_from_item(thd, item, table, copy_func,
+                                          modify_item, convert_blob_length);
+      return create_tmp_field_from_field(thd, (*from_field= field->field),
+                                         item->name, table,
+                                         modify_item ? (Item_field*) item :
+                                                       NULL,
+                                         convert_blob_length);
     }
+    else
+      item= org_item;
   }
   case Item::FUNC_ITEM:
   case Item::COND_ITEM:
@@ -8074,6 +8072,7 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
   case Item::REAL_ITEM:
   case Item::DECIMAL_ITEM:
   case Item::STRING_ITEM:
+  case Item::REF_ITEM:
   case Item::NULL_ITEM:
   case Item::VARBIN_ITEM:
     return create_tmp_field_from_item(thd, item, table, copy_func, modify_item,
@@ -10904,12 +10903,12 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
   usable_keys.set_all();
   for (ORDER *tmp_order=order; tmp_order ; tmp_order=tmp_order->next)
   {
-    if ((*tmp_order->item)->type() != Item::FIELD_ITEM)
+    if ((*tmp_order->item)->real_item()->type() != Item::FIELD_ITEM)
     {
       usable_keys.clear_all();
       DBUG_RETURN(0);
     }
-    usable_keys.intersect(((Item_field*) (*tmp_order->item))->
+    usable_keys.intersect(((Item_field*) (*tmp_order->item)->real_item())->
 			  field->part_of_sortkey);
     if (usable_keys.is_clear_all())
       DBUG_RETURN(0);					// No usable keys