removed incorrect error message about aggregate functions

improved mechanisn of detection posibility to be NULL for single row queries
switched off substitution optimisation for single row subqueries in PS due to problem in resolving substituted expressions
(changes to make subselects test working with PS protocol)

1 files changed, 76 insertions, 15 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index a869e2d24fb..401d4dee20f 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -164,12 +164,7 @@ bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
       thd->where= "checking transformed subquery";
       if (!(*ref)->fixed)
 	ret= (*ref)->fix_fields(thd, tables, ref);
-      // We can't substitute aggregate functions like "SELECT (max(i))"
-      if (substype() == SINGLEROW_SUBS && (*ref)->with_sum_func)
-      {
-	my_error(ER_INVALID_GROUP_FUNC_USE, MYF(0));
-	return 1;
-      }
+      thd->where= save_where;
       return ret;
     }
     // Is it one field subselect?
@@ -322,6 +317,7 @@ Item_singlerow_subselect::select_transformer(JOIN *join)
   if (!select_lex->master_unit()->first_select()->next_select() &&
       !select_lex->table_list.elements &&
       select_lex->item_list.elements == 1 &&
+      !select_lex->item_list.head()->with_sum_func &&
       /*
 	We cant change name of Item_field or Item_ref, because it will
 	prevent it's correct resolving, but we should save name of
@@ -330,7 +326,13 @@ Item_singlerow_subselect::select_transformer(JOIN *join)
 	TODO: solve above problem
       */
       !(select_lex->item_list.head()->type() == FIELD_ITEM ||
-	select_lex->item_list.head()->type() == REF_ITEM)
+	select_lex->item_list.head()->type() == REF_ITEM) &&
+      /*
+        switch off this optimisation for prepare statement,
+        because we do not rollback this changes
+        TODO: make rollback for it, or special name resolving mode in 5.0.
+      */
+      !arena->is_stmt_prepare()
       )
   {
 
@@ -352,9 +354,6 @@ Item_singlerow_subselect::select_transformer(JOIN *join)
     if (join->conds || join->having)
     {
       Item *cond;
-      if (arena->is_stmt_prepare())
-	thd->set_n_backup_item_arena(arena, &backup);
-
       if (!join->having)
 	cond= join->conds;
       else if (!join->conds)
@@ -365,16 +364,12 @@ Item_singlerow_subselect::select_transformer(JOIN *join)
       if (!(substitution= new Item_func_if(cond, substitution,
 					   new Item_null())))
 	goto err;
-      if (arena->is_stmt_prepare())
-        thd->restore_backup_item_arena(arena, &backup);
-    }
+   }
     return RES_REDUCE;
   }
   return RES_OK;
 
 err:
-  if (arena->is_stmt_prepare())
-    thd->restore_backup_item_arena(arena, &backup);
   return RES_ERROR;
 }
 
@@ -401,6 +396,13 @@ void Item_singlerow_subselect::fix_length_and_dec()
     engine->fix_length_and_dec(row);
     value= *row;
   }
+  /*
+    If there are not tables in subquery then ability to have NULL value
+    depends on SELECT list (if single row subquery have tables then it
+    always can be NULL if there are not records fetched).
+  */
+  if (engine->no_tables())
+    maybe_null= engine->may_be_null();
 }
 
 uint Item_singlerow_subselect::cols()
@@ -644,6 +646,7 @@ Item_subselect::trans_res
 Item_in_subselect::single_value_transformer(JOIN *join,
 					    Comp_creator *func)
 {
+  const char *save_where= thd->where;
   DBUG_ENTER("Item_in_subselect::single_value_transformer");
 
   if (changed)
@@ -899,6 +902,7 @@ Item_in_subselect::single_value_transformer(JOIN *join,
 ok:
   if (arena->is_stmt_prepare())
     thd->restore_backup_item_arena(arena, &backup);
+  thd->where= save_where;
   DBUG_RETURN(RES_OK);
 
 err:
@@ -911,6 +915,7 @@ err:
 Item_subselect::trans_res
 Item_in_subselect::row_value_transformer(JOIN *join)
 {
+  const char *save_where= thd->where;
   DBUG_ENTER("Item_in_subselect::row_value_transformer");
 
   if (changed)
@@ -1003,6 +1008,7 @@ Item_in_subselect::row_value_transformer(JOIN *join)
   }
   if (arena->is_stmt_prepare())
     thd->restore_backup_item_arena(arena, &backup);
+  thd->where= save_where;
   DBUG_RETURN(RES_OK);
 
 err:
@@ -1562,3 +1568,58 @@ int subselect_uniquesubquery_engine::change_item(Item_subselect *si,
   DBUG_ASSERT(0);
   return -1;
 }
+
+
+/*
+  Report about presence of tables in subquery
+
+  SINOPSYS
+    subselect_single_select_engine::no_tables()
+
+  RETURN
+    TRUE  there are not tables used in subquery
+    FALSE there are some tables in subquery
+*/
+bool subselect_single_select_engine::no_tables()
+{
+  return(select_lex->table_list.elements == 0);
+}
+
+
+/*
+  Report about presence of tables in subquery
+
+  SINOPSYS
+    subselect_union_engine::no_tables()
+
+  RETURN
+    TRUE  there are not tables used in subquery
+    FALSE there are some tables in subquery
+*/
+bool subselect_union_engine::no_tables()
+{
+  for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
+  {
+    if (sl->table_list.elements)
+      return FALSE;
+  }
+  return TRUE;
+}
+
+
+/*
+  Report about presence of tables in subquery
+
+  SINOPSYS
+    subselect_uniquesubquery_engine::no_tables()
+
+  RETURN
+    TRUE  there are not tables used in subquery
+    FALSE there are some tables in subquery
+*/
+
+bool subselect_uniquesubquery_engine::no_tables()
+{
+  /* returning value is correct, but this method should never be called */
+  return 0;
+}