support of simple row subselects (SCRUM)

mysql-test/r/subselect.result:
  test of simple row subselect
  fixed table droping
mysql-test/t/subselect.test:
  test of simple row subselect
  fixed table dropimg
sql/item.cc:
  Item_cache_str fixed to correctly store NULL and copy string value
sql/item.h:
  Item_cache_str fixed to correctly store NULL and copy string value
sql/item_cmpfunc.cc:
  support of simple row subselects
sql/item_subselect.cc:
  support of simple row subselects
sql/item_subselect.h:
  support of simple row subselects
sql/sql_class.cc:
  support of simple row subselects

mysql-test/r/subselect.result

@@ -52,6 +52,54 @@ a
 SELECT (SELECT 1) as a FROM (SELECT 1) b WHERE (SELECT a) IS NOT NULL;
 a
 1
+SELECT (SELECT 1,2,3) = ROW(1,2,3);
+(SELECT 1,2,3) = ROW(1,2,3)
+1
+SELECT (SELECT 1,2,3) = ROW(1,2,1);
+(SELECT 1,2,3) = ROW(1,2,1)
+0
+SELECT (SELECT 1,2,3) < ROW(1,2,1);
+(SELECT 1,2,3) < ROW(1,2,1)
+0
+SELECT (SELECT 1,2,3) > ROW(1,2,1);
+(SELECT 1,2,3) > ROW(1,2,1)
+1
+SELECT (SELECT 1,2,3) = ROW(1,2,NULL);
+(SELECT 1,2,3) = ROW(1,2,NULL)
+NULL
+SELECT ROW(1,2,3) = (SELECT 1,2,3);
+ROW(1,2,3) = (SELECT 1,2,3)
+1
+SELECT ROW(1,2,3) = (SELECT 1,2,1);
+ROW(1,2,3) = (SELECT 1,2,1)
+0
+SELECT ROW(1,2,3) < (SELECT 1,2,1);
+ROW(1,2,3) < (SELECT 1,2,1)
+0
+SELECT ROW(1,2,3) > (SELECT 1,2,1);
+ROW(1,2,3) > (SELECT 1,2,1)
+1
+SELECT ROW(1,2,3) = (SELECT 1,2,NULL);
+ROW(1,2,3) = (SELECT 1,2,NULL)
+NULL
+SELECT (SELECT 1.5,2,'a') = ROW(1.5,2,'a');
+(SELECT 1.5,2,'a') = ROW(1.5,2,'a')
+1
+SELECT (SELECT 1.5,2,'a') = ROW(1.5,2,'b');
+(SELECT 1.5,2,'a') = ROW(1.5,2,'b')
+0
+SELECT (SELECT 1.5,2,'a') = ROW('b',2,'b');
+(SELECT 1.5,2,'a') = ROW('b',2,'b')
+0
+SELECT (SELECT 'b',2,'a') = ROW(1.5,2,'a');
+(SELECT 'b',2,'a') = ROW(1.5,2,'a')
+0
+SELECT (SELECT 1.5,2,'a') = ROW(1.5,'c','a');
+(SELECT 1.5,2,'a') = ROW(1.5,'c','a')
+0
+SELECT (SELECT 1.5,'c','a') = ROW(1.5,2,'a');
+(SELECT 1.5,'c','a') = ROW(1.5,2,'a')
+0
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8;
 create table t1 (a int);
 create table t2 (a int, b int);
@@ -602,7 +650,7 @@ CREATE TABLE t1 (id int(11) default NULL, KEY id (id)) TYPE=MyISAM CHARSET=latin
 INSERT INTO t1 values (1),(1);
 UPDATE t SET id=(SELECT * FROM t1);
 Subselect returns more than 1 record
-drop table t;
+drop table t, t1;
 create table t (a int);
 insert into t values (1),(2),(3);
 select 1 IN (SELECT * from t);
@@ -705,3 +753,23 @@ select 10.5 > ANY (SELECT * from t);
 10.5 > ANY (SELECT * from t)
 1
 drop table t;
+create table t1 (a int, b int, c varchar(10));
+create table t2 (a int);
+insert into t1 values (1,2,'a'),(2,3,'b'),(3,4,'c');
+insert into t2 values (1),(2),(NULL);
+select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a'),(select c from t1 where a=t2.a)  from t2;
+a	(select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a')	(select c from t1 where a=t2.a)
+1	1	a
+2	0	b
+NULL	NULL	NULL
+select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b'),(select c from t1 where a=t2.a) from t2;
+a	(select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b')	(select c from t1 where a=t2.a)
+1	0	a
+2	1	b
+NULL	NULL	NULL
+select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c'),(select c from t1 where a=t2.a) from t2;
+a	(select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c')	(select c from t1 where a=t2.a)
+1	0	a
+2	0	b
+NULL	NULL	NULL
+drop table t1,t2;

mysql-test/t/subselect.test

@@ -26,6 +26,22 @@ select (SELECT 1 FROM (SELECT 1) a PROCEDURE ANALYSE(1));
 SELECT 1 FROM (SELECT 1) a PROCEDURE ANALYSE((SELECT 1));
 SELECT (SELECT 1) as a FROM (SELECT 1) b WHERE (SELECT a) IS NULL;
 SELECT (SELECT 1) as a FROM (SELECT 1) b WHERE (SELECT a) IS NOT NULL;
+SELECT (SELECT 1,2,3) = ROW(1,2,3);
+SELECT (SELECT 1,2,3) = ROW(1,2,1);
+SELECT (SELECT 1,2,3) < ROW(1,2,1);
+SELECT (SELECT 1,2,3) > ROW(1,2,1);
+SELECT (SELECT 1,2,3) = ROW(1,2,NULL);
+SELECT ROW(1,2,3) = (SELECT 1,2,3);
+SELECT ROW(1,2,3) = (SELECT 1,2,1);
+SELECT ROW(1,2,3) < (SELECT 1,2,1);
+SELECT ROW(1,2,3) > (SELECT 1,2,1);
+SELECT ROW(1,2,3) = (SELECT 1,2,NULL);
+SELECT (SELECT 1.5,2,'a') = ROW(1.5,2,'a');
+SELECT (SELECT 1.5,2,'a') = ROW(1.5,2,'b');
+SELECT (SELECT 1.5,2,'a') = ROW('b',2,'b');
+SELECT (SELECT 'b',2,'a') = ROW(1.5,2,'a');
+SELECT (SELECT 1.5,2,'a') = ROW(1.5,'c','a');
+SELECT (SELECT 1.5,'c','a') = ROW(1.5,2,'a');
 
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8;
 create table t1 (a int);
@@ -363,7 +379,7 @@ CREATE TABLE t1 (id int(11) default NULL, KEY id (id)) TYPE=MyISAM CHARSET=latin
 INSERT INTO t1 values (1),(1);
 -- error 1240
 UPDATE t SET id=(SELECT * FROM t1);
-drop table t;
+drop table t, t1;
 
 
 #NULL test
@@ -409,3 +425,12 @@ select 10.5 > ALL (SELECT * from t);
 select 1.5 > ANY (SELECT * from t);
 select 10.5 > ANY (SELECT * from t);
 drop table t;
+
+create table t1 (a int, b int, c varchar(10));
+create table t2 (a int);
+insert into t1 values (1,2,'a'),(2,3,'b'),(3,4,'c');
+insert into t2 values (1),(2),(NULL);
+select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a'),(select c from t1 where a=t2.a)  from t2;
+select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b'),(select c from t1 where a=t2.a) from t2;
+select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c'),(select c from t1 where a=t2.a) from t2;
+drop table t1,t2;

sql/item.cc

@@ -1217,6 +1217,60 @@ bool field_is_equal_to_item(Field *field,Item *item)
   return result == field->val_real();
 }
 
+Item_cache* Item_cache::get_cache(Item_result type)
+{
+  switch (type)
+  {
+  case INT_RESULT:
+    return new Item_cache_int();
+  case REAL_RESULT:
+    return new Item_cache_real();
+  case STRING_RESULT:
+    return new Item_cache_str();
+  default:
+    // should never be in real life
+    DBUG_ASSERT(0);
+    return 0;
+  }
+}
+
+void Item_cache_str::store(Item *item)
+{
+  str_value.set(buffer, sizeof(buffer), item->charset());
+  value= item->str_result(&str_value);
+  if ((null_value= item->null_value))
+    value= 0;
+  else if (value != &str_value)
+  {
+    /*
+      We copy string value to avoid changing value if 'item' is table field
+      in queries like following (where t1.c is varchar):
+      select a, 
+             (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a'),
+             (select c from t1 where a=t2.a)
+        from t2;
+    */
+    str_value.copy(*value);
+    value= &str_value;
+  }
+
+}
+double Item_cache_str::val()
+{ 
+  if (value)
+    return my_strntod(value->charset(), value->ptr(),
+		      value->length(), (char**)0);
+  else
+    return (double)0;
+}
+longlong Item_cache_str::val_int()
+{
+  if (value)
+    return my_strntoll(value->charset(), value->ptr(),
+		       value->length(), (char**) 0, 10);
+  else
+    return (longlong)0;
+}
 
 /*****************************************************************************
 ** Instantiate templates

sql/item.h

@@ -103,7 +103,9 @@ class Item {
   virtual Item** addr(uint i) { return 0; }
   virtual bool check_cols(uint c);
   // It is not row => null inside is impossible
-  virtual bool null_inside() { return 0; };
+  virtual bool null_inside() { return 0; }
+  // used in row subselects to get value of elements
+  virtual void bring_value() {}
 };
 
 
@@ -719,6 +721,7 @@ class Item_cache: public Item
     decimals= dec;
   }
   enum Type type() const { return CACHE_ITEM; }
+  static Item_cache* get_cache(Item_result type);
 };
 
 class Item_cache_int: public Item_cache
@@ -766,24 +769,9 @@ class Item_cache_str: public Item_cache
 public:
   Item_cache_str() { fixed= 1; null_value= 1; }
   
-  void store(Item *item)
-  {
-    str_value.set(buffer, sizeof(buffer), item->charset());
-    value= item->str_result(&str_value);
-    // TODO remove if str_value charset have no side effect for now
-    str_value.set_charset(value->charset());
-    null_value= item->null_value;
-  }
-  double val()
-  { 
-    return my_strntod(value->charset(), value->ptr(),
-		      value->length(), (char**)0);
-  }
-  longlong val_int()
-  {
-    return my_strntoll(value->charset(), value->ptr(),
-		       value->length(), (char**) 0, 10);
-  }
+  void store(Item *item);
+  double val();
+  longlong val_int();
   String* val_str(String *) { return value; }
   enum Item_result result_type() const { return STRING_RESULT; }
   CHARSET_INFO *charset() const { return value->charset(); };

sql/item_cmpfunc.cc

@@ -247,6 +247,8 @@ int Arg_comparator::compare_e_int()
 int Arg_comparator::compare_row()
 {
   int res= 0;
+  (*a)->bring_value();
+  (*b)->bring_value();
   uint n= (*a)->cols();
   for (uint i= 0; i<n; i++)
   {
@@ -261,6 +263,8 @@ int Arg_comparator::compare_row()
 int Arg_comparator::compare_e_row()
 {
   int res= 0;
+  (*a)->bring_value();
+  (*b)->bring_value();
   uint n= (*a)->cols();
   for (uint i= 0; i<n; i++)
   {
@@ -1219,6 +1223,7 @@ void cmp_item_row::store_value(Item *item)
   n= item->cols();
   if ((comparators= (cmp_item **) thd->alloc(sizeof(cmp_item *)*n)))
   {
+    item->bring_value();
     item->null_value= 0;
     for (uint i=0; i < n; i++)
       if ((comparators[i]= cmp_item::get_comparator(item->el(i))))
@@ -1252,6 +1257,7 @@ void cmp_item_row::store_value_by_template(cmp_item *t, Item *item)
   n= tmpl->n;
   if ((comparators= (cmp_item **) sql_alloc(sizeof(cmp_item *)*n)))
   {
+    item->bring_value();
     item->null_value= 0;
     for (uint i=0; i < n; i++)
       if ((comparators[i]= tmpl->comparators[i]->make_same()))
@@ -1284,6 +1290,7 @@ int cmp_item_row::cmp(Item *arg)
     return 1;
   }
   bool was_null= 0;
+  arg->bring_value();
   for (uint i=0; i < n; i++)
     if (comparators[i]->cmp(arg->el(i)))
     {

sql/item_subselect.cc

@@ -112,9 +112,14 @@ bool Item_subselect::check_loop(uint id)
   DBUG_RETURN(engine->check_loop(id));
 }
 
+Item::Type Item_subselect::type() const 
+{
+  return SUBSELECT_ITEM;
+}
+
 void Item_subselect::fix_length_and_dec()
 {
-  engine->fix_length_and_dec();
+  engine->fix_length_and_dec(0);
 }
 
 inline table_map Item_subselect::used_tables() const
@@ -130,6 +135,7 @@ Item_singleval_subselect::Item_singleval_subselect(THD *thd,
   init(thd, select_lex, new select_singleval_subselect(this));
   max_columns= 1;
   maybe_null= 1;
+  max_columns= UINT_MAX;
   DBUG_VOID_RETURN;
 }
 
@@ -140,9 +146,9 @@ void Item_singleval_subselect::reset()
     value->null_value= 1;
 }
 
-void Item_singleval_subselect::store(Item *item)
+void Item_singleval_subselect::store(uint i, Item *item)
 {
-  value->store(item);
+  row[i]->store(item);
 }
 
 enum Item_result Item_singleval_subselect::result_type() const
@@ -152,29 +158,58 @@ enum Item_result Item_singleval_subselect::result_type() const
 
 void Item_singleval_subselect::fix_length_and_dec()
 {
-  engine->fix_length_and_dec();
-  switch (engine->type())
+  if ((max_columns= engine->cols()) == 1)
+  {
+    engine->fix_length_and_dec(row= &value);
+    if (!(value= Item_cache::get_cache(engine->type())))
+    {
+      my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
+      current_thd->fatal_error= 1;
+      return;
+    }  
+  }
+  else
   {
-  case INT_RESULT:
-    value= new Item_cache_int();
-    break;
-  case REAL_RESULT:
-    value= new Item_cache_real();
-    break;
-  case STRING_RESULT:
-    value= new Item_cache_str();
-    break;
-  default:
-    // should never be in real life
-    DBUG_ASSERT(0);
-    return;
+    THD *thd= current_thd;
+    if (!(row= (Item_cache**)thd->alloc(sizeof(Item_cache*)*max_columns)))
+    {
+      my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
+      thd->fatal_error= 1;
+      return;
+    }
+    engine->fix_length_and_dec(row);
+    value= *row;
   }
-  value->set_len_n_dec(max_length, decimals);
 }
 
-Item::Type Item_subselect::type() const 
+uint Item_singleval_subselect::cols()
 {
-  return SUBSELECT_ITEM;
+  return engine->cols();
+}
+
+bool Item_singleval_subselect::check_cols(uint c)
+{
+  if (c != engine->cols())
+  {
+    my_error(ER_CARDINALITY_COL, MYF(0), c);
+    return 1;
+  }
+  return 0;
+}
+
+bool Item_singleval_subselect::null_inside()
+{
+  for (uint i= 0; i < max_columns ; i++)
+  {
+    if (row[i]->null_value)
+      return 1;
+  }
+  return 0;
+}
+
+void Item_singleval_subselect::bring_value()
+{
+  engine->exec();
 }
 
 double Item_singleval_subselect::val () 
@@ -268,7 +303,7 @@ Item_allany_subselect::Item_allany_subselect(THD *thd, Item * left_exp,
 
 void Item_exists_subselect::fix_length_and_dec()
 {
-   decimals=0;
+   decimals= 0;
    max_length= 1;
 }
 
@@ -540,31 +575,85 @@ int subselect_union_engine::prepare()
   return unit->prepare(thd, result);
 }
 
-void subselect_single_select_engine::fix_length_and_dec()
+static Item_result set_row(SELECT_LEX *select_lex, Item * item,
+			   Item_cache **row)
 {
+  Item_result res_type= STRING_RESULT;
+  Item *sel_item;
   List_iterator_fast<Item> li(select_lex->item_list);
-  Item *sel_item= li++;
-  item->max_length= sel_item->max_length;
-  res_type= sel_item->result_type();
-  item->decimals= sel_item->decimals;
+  for (uint i= 0; (sel_item= li++); i++)
+  {
+    item->max_length= sel_item->max_length;
+    res_type= sel_item->result_type();
+    item->decimals= sel_item->decimals;
+    if (row)
+    {
+      if (!(row[i]= Item_cache::get_cache(res_type)))
+      {
+	my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
+	current_thd->fatal_error= 1;
+	return STRING_RESULT; // we should return something
+      }
+      row[i]->set_len_n_dec(sel_item->max_length, sel_item->decimals);
+    }
+  }
+  if (select_lex->item_list.elements > 1)
+    res_type= ROW_RESULT;
+  return res_type;
 }
 
-void subselect_union_engine::fix_length_and_dec()
+void subselect_single_select_engine::fix_length_and_dec(Item_cache **row)
 {
-  uint32 mlen= 0, len;
-  Item *sel_item= 0;
-  for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
+  DBUG_ASSERT(row || select_lex->item_list.elements==1);
+  res_type= set_row(select_lex, item, row);
+}
+
+void subselect_union_engine::fix_length_and_dec(Item_cache **row)
+{
+  DBUG_ASSERT(row || unit->first_select()->item_list.elements==1);
+
+  if (unit->first_select()->item_list.elements == 1)
   {
-    List_iterator_fast<Item> li(sl->item_list);
-    Item *s_item= li++;
-    if ((len= s_item->max_length))
-      mlen= len;
-    if (!sel_item)
-      sel_item= s_item;
+    uint32 mlen= 0, len;
+    Item *sel_item= 0;
+    for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
+    {
+      List_iterator_fast<Item> li(sl->item_list);
+      Item *s_item= li++;
+      if ((len= s_item->max_length) > mlen)
+	mlen= len;
+      if (!sel_item)
+	sel_item= s_item;
+    }
+    item->max_length= mlen;
+    res_type= sel_item->result_type();
+    item->decimals= sel_item->decimals;
+    if (row)
+    {
+      if (!(row[0]= Item_cache::get_cache(res_type)))
+      {
+	my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
+	current_thd->fatal_error= 1;
+	return;
+      }
+      row[0]->set_len_n_dec(mlen, sel_item->decimals);
+    }
+  }
+  else
+  {
+    SELECT_LEX *sl= unit->first_select();
+    res_type= set_row(sl, item, row);
+    for(sl= sl->next_select(); sl; sl->next_select())
+    {
+      List_iterator_fast<Item> li(sl->item_list);
+      Item *sel_item;
+      for (uint i= 0; (sel_item= li++); i++)
+      {
+	if (sel_item->max_length > row[i]->max_length)
+	  row[i]->max_length= sel_item->max_length;
+      }
+    }
   }
-  item->max_length= mlen;
-  res_type= sel_item->result_type();
-  item->decimals= sel_item->decimals;
 }
 
 int subselect_single_select_engine::exec()

sql/item_subselect.h

@@ -94,8 +94,7 @@ class Item_cache;
 class Item_singleval_subselect :public Item_subselect
 {
 protected:
-  Item_cache *value;
-  
+  Item_cache *value, **row;
 public:
   Item_singleval_subselect(THD *thd, st_select_lex *select_lex);
   Item_singleval_subselect(Item_singleval_subselect *item):
@@ -106,7 +105,7 @@ class Item_singleval_subselect :public Item_subselect
     decimals= item->decimals;
   }
   void reset();
-  void store(Item* item);
+  void store(uint i, Item* item);
   double val();
   longlong val_int ();
   String *val_str (String *);
@@ -114,6 +113,13 @@ class Item_singleval_subselect :public Item_subselect
   enum Item_result result_type() const;
   void fix_length_and_dec();
 
+  uint cols();
+  Item* el(uint i) { return (Item*)row[i]; }
+  Item** addr(uint i) { return (Item**)row + i; }
+  bool check_cols(uint c);
+  bool null_inside();
+  void bring_value();
+
   friend class select_singleval_subselect;
 };
 
@@ -212,7 +218,7 @@ class subselect_engine
   }
 
   virtual int prepare()= 0;
-  virtual void fix_length_and_dec()= 0;
+  virtual void fix_length_and_dec(Item_cache** row)= 0;
   virtual int exec()= 0;
   virtual uint cols()= 0; /* return number of columnss in select */
   virtual bool depended()= 0; /* depended from outer select */
@@ -233,7 +239,7 @@ class subselect_single_select_engine: public subselect_engine
 				 select_subselect *result,
 				 Item_subselect *item);
   int prepare();
-  void fix_length_and_dec();
+  void fix_length_and_dec(Item_cache** row);
   int exec();
   uint cols();
   bool depended();
@@ -250,7 +256,7 @@ class subselect_union_engine: public subselect_engine
 			 select_subselect *result,
 			 Item_subselect *item);
   int prepare();
-  void fix_length_and_dec();
+  void fix_length_and_dec(Item_cache** row);
   int exec();
   uint cols();
   bool depended();

sql/sql_class.cc

@@ -931,8 +931,9 @@ bool select_singleval_subselect::send_data(List<Item> &items)
     DBUG_RETURN(0);
   }
   List_iterator_fast<Item> li(items);
-  Item *val_item= li++;                   // Only one (single value subselect)
-  it->store(val_item);
+  Item *val_item;
+  for (uint i= 0; (val_item= li++); i++)
+    it->store(i, val_item);
   it->assigned(1);
   DBUG_RETURN(0);
 }