fixed * without tables in IN bug

fixed sunction-test select in IN bug
fixed unions in subselect bug


include/mysqld_error.h:
  new warning
mysql-test/r/subselect.result:
  test of * without tables in IN
  test of sunction-test select in IN
  test of unions in subselect
mysql-test/t/subselect.test:
  test of * without tables in IN
  test of sunction-test select in IN
  test of unions in subselect
sql/item.cc:
  fixed * substitution without tables
sql/item_subselect.cc:
  fixed subselect rewriting with function-test subselect
sql/item_subselect.h:
  mechanism for subselect removing
sql/share/czech/errmsg.txt:
  new warning
sql/share/danish/errmsg.txt:
  new warning
sql/share/dutch/errmsg.txt:
  new warning
sql/share/english/errmsg.txt:
  new warning
sql/share/estonian/errmsg.txt:
  new warning
sql/share/french/errmsg.txt:
  new warning
sql/share/german/errmsg.txt:
  new warning
sql/share/greek/errmsg.txt:
  new warning
sql/share/hungarian/errmsg.txt:
  new warning
sql/share/italian/errmsg.txt:
  new warning
sql/share/japanese/errmsg.txt:
  new warning
sql/share/korean/errmsg.txt:
  new warning
sql/share/norwegian-ny/errmsg.txt:
  new warning
sql/share/norwegian/errmsg.txt:
  new warning
sql/share/polish/errmsg.txt:
  new warning
sql/share/portuguese/errmsg.txt:
  new warning
sql/share/romanian/errmsg.txt:
  new warning
sql/share/russian/errmsg.txt:
  new warning
sql/share/serbian/errmsg.txt:
  new warning
sql/share/slovak/errmsg.txt:
  new warning
sql/share/spanish/errmsg.txt:
  new warning
sql/share/swedish/errmsg.txt:
  new warning
sql/share/ukrainian/errmsg.txt:
  new warning
sql/sql_base.cc:
  fixed case on no name field in UNION subselect
sql/sql_lex.cc:
  mechanisp of removing single subselect for optimisation purposes
sql/sql_lex.h:
  mechanisp of removing single subselect for optimisation purposes
sql/sql_parse.cc:
  error handling
sql/sql_union.cc:
  fixed unions in subselect
sql/sql_yacc.yy:
  fixed Lex->describe flag appearence

32 files changed, 156 insertions, 38 deletions

diff --git a/sql/item.cc b/sql/item.cc
index ece627f9fe3..a81b4f2394b 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -463,41 +463,41 @@ bool Item_asterisk_remover::fix_fields(THD *thd,
 	((Item_field*) item)->field_name[0] == '*')
     {
       Item_field *fitem=  (Item_field*) item;
-      if (!list->next || fitem->db_name || fitem->table_name)
-      {
-	TABLE_LIST *table= find_table_in_list(list,
-					      fitem->db_name,
-					      fitem->table_name);
-	if (table)
+      if (list)
+	if (!list->next || fitem->db_name || fitem->table_name)
 	{
-	  TABLE * tb= table->table;
-	  if (find_table_in_list(table->next, fitem->db_name,
-				 fitem->table_name) != 0 ||
-	      tb->fields == 1)
+	  TABLE_LIST *table= find_table_in_list(list,
+						fitem->db_name,
+						fitem->table_name);
+	  if (table)
 	  {
-	    if ((item= new Item_field(tb->field[0])))
+	    TABLE * tb= table->table;
+	    if (find_table_in_list(table->next, fitem->db_name,
+				   fitem->table_name) != 0 ||
+		tb->fields == 1)
 	    {
-	      res= 0;
-	      tb->field[0]->query_id= thd->query_id;
-	      tb->used_keys&= tb->field[0]->part_of_key;
-	      tb->used_fields= tb->fields;
+	      if ((item= new Item_field(tb->field[0])))
+	      {
+		res= 0;
+		tb->field[0]->query_id= thd->query_id;
+		tb->used_keys&= tb->field[0]->part_of_key;
+		tb->used_fields= tb->fields;
+	      }
+	      else
+		thd->fatal_error= 1; // can't create Item => out of memory
 	    }
 	    else
-	      thd->fatal_error= 1; // can't create Item => out of memory
+	      my_message(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL),
+			 MYF(0));
 	  }
 	  else
-	    my_message(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL),
-		       MYF(0));
+	    my_error(ER_BAD_TABLE_ERROR, MYF(0), fitem->table_name);
 	}
 	else
-	  if (!fitem->table_name)
-	    my_error(ER_NO_TABLES_USED, MYF(0));
-	  else
-	    my_error(ER_BAD_TABLE_ERROR, MYF(0), fitem->table_name);
-      }
+	  my_message(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL),
+		     MYF(0));
       else
-	my_message(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL),
-		   MYF(0));
+	my_error(ER_NO_TABLES_USED, MYF(0));
     }   
     else
       res= item->fix_fields(thd, list, &item);
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 555b7ae45c3..e0bfbe01c9b 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -33,7 +33,7 @@ SUBSELECT TODO:
 #include "sql_select.h"
 
 Item_subselect::Item_subselect():
-  Item_result_field(), engine_owner(1), value_assigned(0)
+  Item_result_field(), engine_owner(1), value_assigned(0), substitution(0)
 {
   assign_null();
   /*
@@ -89,6 +89,13 @@ void Item_subselect::make_field (Send_field *tmp_field)
 
 bool Item_subselect::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  if (substitution)
+  {
+    (*ref)= substitution;
+    engine->exclude();
+    return substitution->fix_fields(thd, tables, ref);
+  }
+
   char const *save_where= thd->where;
   int res= engine->prepare();
   if (!res)
@@ -291,12 +298,12 @@ void Item_in_subselect::single_value_transformer(st_select_lex *select_lex,
     else
       item= (Item*) sl->item_list.pop();
 
-    left_expr= new Item_outer_select_context_saver(left_expr);
+    Item *expr= new Item_outer_select_context_saver(left_expr);
 
     if (sl->having || sl->with_sum_func || sl->group_list.first)
     {
       sl->item_list.push_back(item);
-      item= (*func)(left_expr, new Item_ref(sl->item_list.head_ref(),
+      item= (*func)(expr, new Item_ref(sl->item_list.head_ref(),
 					    0, "<result>"));
       if (sl->having)
 	sl->having= new Item_cond_and(sl->having, item);
@@ -307,11 +314,42 @@ void Item_in_subselect::single_value_transformer(st_select_lex *select_lex,
     {
       sl->item_list.empty();
       sl->item_list.push_back(new Item_int(1));
-      item= (*func)(left_expr, new Item_asterisk_remover(item));
-      if (sl->where)
-	sl->where= new Item_cond_and(sl->where, item);
+      if (sl->table_list.elements)
+      {
+	item= (*func)(expr, new Item_asterisk_remover(item));
+	if (sl->where)
+	  sl->where= new Item_cond_and(sl->where, item);
+	else
+	  sl->where= item;
+      }
       else
-	sl->where= item;
+      {
+	if (item->type() == Item::FIELD_ITEM &&
+	    ((Item_field*) item)->field_name[0] == '*')
+	{
+	  my_error(ER_NO_TABLES_USED, MYF(0));
+	  DBUG_VOID_RETURN;
+	}
+	if (select_lex->next_select())
+	{
+	  // it is in union => we should perform it
+	  sl->having= (*func)(expr, item);
+	}
+	else
+	{
+	  // it is single select without tables => possible optimization
+	  item= (*func)(left_expr, item);
+	  substitution= item;
+	  THD *thd= current_thd;
+	  if (thd->lex.describe)
+	  {
+	    char warn_buff[MYSQL_ERRMSG_SIZE];
+	    sprintf(warn_buff, ER(ER_SELECT_REDUCED), sl->select_number);
+	    push_warning(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
+			 ER_SELECT_REDUCED, warn_buff);
+	  }
+	}
+      }
     }
   }
   DBUG_VOID_RETURN;
@@ -502,3 +540,17 @@ bool subselect_union_engine::check_loop(uint id)
       DBUG_RETURN(1);
   DBUG_RETURN(0);
 }
+
+void subselect_single_select_engine::exclude()
+{
+  select_lex->master_unit()->exclude_level();
+  //if (current_thd->lex->describe)
+}
+
+void subselect_union_engine::exclude()
+{
+  unit->exclude_level();
+  // for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
+  //  if (sl->join && sl->join->check_loop(id))
+  //    DBUG_RETURN(1);
+}
diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index 3a635ace8ba..d323dab51f1 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -36,6 +36,8 @@ class Item_subselect :public Item_result_field
   my_bool engine_owner; /* Is this item owner of engine */
   my_bool value_assigned; /* value already assigned to subselect */
 protected:
+  /* substitution instead of subselect in case of optimization */
+  Item *substitution;
   /* engine that perform execution of subselect (single select or union) */
   subselect_engine *engine; 
   /* allowed number of columns (1 for single value subqueries) */
@@ -45,6 +47,7 @@ public:
   Item_subselect();
   Item_subselect(Item_subselect *item)
   {
+    substitution= item->substitution;
     null_value= item->null_value;
     decimals= item->decimals;
     max_columns= item->max_columns;
@@ -213,6 +216,7 @@ public:
   virtual bool depended()= 0; /* depended from outer select */
   enum Item_result type() { return res_type; }
   virtual bool check_loop(uint id)= 0;
+  virtual void exclude()= 0;
 };
 
 class subselect_single_select_engine: public subselect_engine
@@ -232,6 +236,7 @@ public:
   uint cols();
   bool depended();
   bool check_loop(uint id);
+  void exclude();
 };
 
 class subselect_union_engine: public subselect_engine
@@ -248,4 +253,5 @@ public:
   uint cols();
   bool depended();
   bool check_loop(uint id);
+  void exclude();
 };
diff --git a/sql/share/czech/errmsg.txt b/sql/share/czech/errmsg.txt
index 4838de12ed6..ff73914199f 100644
--- a/sql/share/czech/errmsg.txt
+++ b/sql/share/czech/errmsg.txt
@@ -256,3 +256,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/danish/errmsg.txt b/sql/share/danish/errmsg.txt
index 91fa06f184f..f0c78032814 100644
--- a/sql/share/danish/errmsg.txt
+++ b/sql/share/danish/errmsg.txt
@@ -250,3 +250,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/dutch/errmsg.txt b/sql/share/dutch/errmsg.txt
index 50c70ce0d2c..cf8d7ecc6b3 100644
--- a/sql/share/dutch/errmsg.txt
+++ b/sql/share/dutch/errmsg.txt
@@ -258,3 +258,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/english/errmsg.txt b/sql/share/english/errmsg.txt
index 1c5564b9ad5..963ba7a29bf 100644
--- a/sql/share/english/errmsg.txt
+++ b/sql/share/english/errmsg.txt
@@ -247,3 +247,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/estonian/errmsg.txt b/sql/share/estonian/errmsg.txt
index 8a49cc7fb69..759f569e396 100644
--- a/sql/share/estonian/errmsg.txt
+++ b/sql/share/estonian/errmsg.txt
@@ -252,3 +252,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/french/errmsg.txt b/sql/share/french/errmsg.txt
index a8b602ee295..de2d7ee6854 100644
--- a/sql/share/french/errmsg.txt
+++ b/sql/share/french/errmsg.txt
@@ -247,3 +247,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/german/errmsg.txt b/sql/share/german/errmsg.txt
index cb449738d61..166d604e013 100644
--- a/sql/share/german/errmsg.txt
+++ b/sql/share/german/errmsg.txt
@@ -250,3 +250,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/greek/errmsg.txt b/sql/share/greek/errmsg.txt
index f6c650468b1..9533c25a30d 100644
--- a/sql/share/greek/errmsg.txt
+++ b/sql/share/greek/errmsg.txt
@@ -247,3 +247,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/hungarian/errmsg.txt b/sql/share/hungarian/errmsg.txt
index fe47d79a101..07597be6214 100644
--- a/sql/share/hungarian/errmsg.txt
+++ b/sql/share/hungarian/errmsg.txt
@@ -249,3 +249,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/italian/errmsg.txt b/sql/share/italian/errmsg.txt
index 0d951857392..772f7ba9532 100644
--- a/sql/share/italian/errmsg.txt
+++ b/sql/share/italian/errmsg.txt
@@ -247,3 +247,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/japanese/errmsg.txt b/sql/share/japanese/errmsg.txt
index df78901a6e9..42b77e56f6b 100644
--- a/sql/share/japanese/errmsg.txt
+++ b/sql/share/japanese/errmsg.txt
@@ -249,3 +249,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/korean/errmsg.txt b/sql/share/korean/errmsg.txt
index c20110e1aa5..b6a8a403213 100644
--- a/sql/share/korean/errmsg.txt
+++ b/sql/share/korean/errmsg.txt
@@ -247,3 +247,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/norwegian-ny/errmsg.txt b/sql/share/norwegian-ny/errmsg.txt
index c75c3ed6140..54cb3bb77e3 100644
--- a/sql/share/norwegian-ny/errmsg.txt
+++ b/sql/share/norwegian-ny/errmsg.txt
@@ -249,3 +249,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/norwegian/errmsg.txt b/sql/share/norwegian/errmsg.txt
index b5a660773ab..9a6a5f5e427 100644
--- a/sql/share/norwegian/errmsg.txt
+++ b/sql/share/norwegian/errmsg.txt
@@ -249,3 +249,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/polish/errmsg.txt b/sql/share/polish/errmsg.txt
index c65a16bf1e4..6488ca27782 100644
--- a/sql/share/polish/errmsg.txt
+++ b/sql/share/polish/errmsg.txt
@@ -251,3 +251,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/portuguese/errmsg.txt b/sql/share/portuguese/errmsg.txt
index 355ae90c157..1e50e8bff5e 100644
--- a/sql/share/portuguese/errmsg.txt
+++ b/sql/share/portuguese/errmsg.txt
@@ -247,3 +247,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/romanian/errmsg.txt b/sql/share/romanian/errmsg.txt
index c7a5b41deac..d999661a40b 100644
--- a/sql/share/romanian/errmsg.txt
+++ b/sql/share/romanian/errmsg.txt
@@ -251,3 +251,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s"
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/russian/errmsg.txt b/sql/share/russian/errmsg.txt
index 35134e6d9d5..fb4278c2ae9 100644
--- a/sql/share/russian/errmsg.txt
+++ b/sql/share/russian/errmsg.txt
@@ -250,3 +250,4 @@
 "Циклическая ссылка на подзапрос",
 "Преобразование поля '%s' из %s в %s",
 "Ссылка '%-.64s' не поддерживается (%s)",
+"Select %u был упразднен в процессе оптимизации",
diff --git a/sql/share/serbian/errmsg.txt b/sql/share/serbian/errmsg.txt
index 354c0bdfac4..526f5834094 100644
--- a/sql/share/serbian/errmsg.txt
+++ b/sql/share/serbian/errmsg.txt
@@ -243,3 +243,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/slovak/errmsg.txt b/sql/share/slovak/errmsg.txt
index 4f49aeb2f6e..db06c0f4881 100644
--- a/sql/share/slovak/errmsg.txt
+++ b/sql/share/slovak/errmsg.txt
@@ -255,3 +255,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/spanish/errmsg.txt b/sql/share/spanish/errmsg.txt
index 1bd4aed6897..40d36a571f2 100644
--- a/sql/share/spanish/errmsg.txt
+++ b/sql/share/spanish/errmsg.txt
@@ -248,3 +248,4 @@
 "Cyclic reference on subqueries",
 "Converting column '%s' from %s to %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/swedish/errmsg.txt b/sql/share/swedish/errmsg.txt
index af3f7ca33dd..817d8acbfef 100644
--- a/sql/share/swedish/errmsg.txt
+++ b/sql/share/swedish/errmsg.txt
@@ -247,3 +247,4 @@
 "Syklisk referens i subselect",
 "Konvertar kolumn '%s' frЕn %s till %s",
 "Reference '%-.64s' not supported (%s)",
+"Select %u was reduced during optimisation",
diff --git a/sql/share/ukrainian/errmsg.txt b/sql/share/ukrainian/errmsg.txt
index c5bfff130fd..a95043f9fcd 100644
--- a/sql/share/ukrainian/errmsg.txt
+++ b/sql/share/ukrainian/errmsg.txt
@@ -252,3 +252,4 @@
 "Циклiчне посилання на пiдзапит",
 "Перетворення стовбца '%s' з %s у %s",
 "Посилання '%-.64s' не пiдтримуется (%s)",
+"Select %u was скасовано при оптимiзацii",
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 8aa33a65ce3..b052fb066e0 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -2082,7 +2082,7 @@ int setup_fields(THD *thd, TABLE_LIST *tables, List<Item> &fields,
 
   while ((item=it++))
   {
-    if (item->type() == Item::FIELD_ITEM &&
+    if (item->type() == Item::FIELD_ITEM && ((Item_field*) item)->field_name &&
 	((Item_field*) item)->field_name[0] == '*')
     {
       uint elem= fields.elements;
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 5104487c700..041e9c1d892 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -1058,6 +1058,31 @@ void st_select_lex_node::exclude()
   */
 }
 
+void st_select_lex_unit::exclude_level()
+{
+  SELECT_LEX_UNIT *units= 0, **units_last= &units;
+  for(SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
+  {
+    if (sl->link_prev && (*sl->link_prev= sl->link_next))
+      sl->link_next->link_prev= sl->link_prev;
+    SELECT_LEX_UNIT **last= 0;
+    for (SELECT_LEX_UNIT *u= sl->first_inner_unit(); u; u= u->next_unit())
+      last= (SELECT_LEX_UNIT**)&(u->next);
+    if (last)
+    {
+      (*units_last)= sl->first_inner_unit();
+      units_last= last;
+    }
+  }
+  if (units)
+  {
+    (*prev)= units;
+    (*units_last)= (SELECT_LEX_UNIT*)next;
+  }
+  else
+    (*prev)= next;
+}
+
 st_select_lex* st_select_lex_node::select_lex()
 {
   DBUG_ENTER("st_select_lex_node::select_lex (never should be called)");
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index b9691bb1059..4c5ca88b7b0 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -242,6 +242,8 @@ public:
 					List<String> *ignore_index= 0);
   virtual void set_lock_for_tables(thr_lock_type lock_type) {}
   void mark_as_dependent(st_select_lex *last);
+
+  friend class st_select_lex_unit;
 private:
   void fast_exclude();
 };
@@ -288,6 +290,7 @@ public:
   st_select_lex* outer_select();
   st_select_lex* first_select() { return (st_select_lex*) slave; }
   st_select_lex_unit* next_unit() { return (st_select_lex_unit*) next; }
+  void st_select_lex_unit::exclude_level();
 
   /* UNION methods */
   int prepare(THD *thd, select_result *result);
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index a410a9f2d7e..26817bc30ac 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -1329,7 +1329,6 @@ mysql_execute_command(THD *thd)
   */
   thd->old_total_warn_count= thd->total_warn_count;
 
-  thd->net.report_error= 0;
   if (thd->slave_thread)
   {
     /* 
@@ -2957,6 +2956,8 @@ mysql_parse(THD *thd, char *inBuf, uint length)
 
   mysql_init_query(thd);
   thd->query_length = length;
+  thd->net.report_error= 0;
+
   if (query_cache_send_result_to_client(thd, inBuf, length) <= 0)
   {
     LEX *lex=lex_start(thd, (uchar*) inBuf, length);
@@ -2969,8 +2970,13 @@ mysql_parse(THD *thd, char *inBuf, uint length)
       }
       else
       {
-	mysql_execute_command(thd);
-	query_cache_end_of_result(&thd->net);
+	if (thd->net.report_error)
+	  send_error(thd, 0, NullS);
+	else
+	{
+	  mysql_execute_command(thd);
+	  query_cache_end_of_result(&thd->net);
+	}
       }
     }
     else
diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index 0e6de306c0d..d448a5204e2 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -214,7 +214,11 @@ int st_select_lex_unit::exec()
   if (dependent || !item || !item->assigned())
   {
     if (optimized && item && item->assigned())
+    {
       item->assigned(0); // We will reinit & rexecute unit
+      item->assign_null();
+      table->file->delete_all_rows();
+    }
     for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
     {
       thd->lex.current_select= sl;
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index cb1c7fed838..c4b3c31d91b 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -3323,11 +3323,10 @@ describe:
 	    YYABORT;
 	}
 	opt_describe_column
-	| describe_command select
+	| describe_command { Lex->describe=1; } select
           { 
 	    LEX *lex=Lex;
 	    lex->select_lex.options|= SELECT_DESCRIBE; 
-	    lex->describe=1;
 	  };