EXISTS type of subselect

more correct parameters in result creation script

mysql-test/create-test-result

@@ -32,7 +32,7 @@ result_file=$RESULT_DIR/$test_name.result
 
 touch $result_file
 echo "Running the test case against empty file, will fail, but don't worry"
-./mysql-test-run --do-test=$test_name
+./mysql-test-run --local $test_name
 
 reject_file=$result_file.reject
 

mysql-test/r/subselect.result

@@ -67,4 +67,11 @@ b	(select avg(t2.a+(select min(t3.a) from t3 where t3.a >= t4.a)) from t2)
 8	7.5000
 8	6.0000
 9	5.5000
+select * from t3 where exists (select * from t2 where t2.b=t3.a);
+a
+7
+select * from t3 where not exists (select * from t2 where t2.b=t3.a);
+a
+6
+3
 drop table t1,t2,t3,t4;

mysql-test/t/subselect.test

@@ -26,4 +26,6 @@ select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from
 select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3 where t3.a > t1.a) order by 1 desc limit 1);
 select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3 where t3.a < t1.a) order by 1 desc limit 1);
 select b,(select avg(t2.a+(select min(t3.a) from t3 where t3.a >= t4.a)) from t2) from t4;
+select * from t3 where exists (select * from t2 where t2.b=t3.a);
+select * from t3 where not exists (select * from t2 where t2.b=t3.a);
 drop table t1,t2,t3,t4;

sql/item_subselect.cc

@@ -35,12 +35,13 @@ SUBSELECT TODO:
 #include "mysql_priv.h"
 #include "sql_select.h"
 
-Item_subselect::Item_subselect(THD *thd, st_select_lex *select_lex):
+Item_subselect::Item_subselect(THD *thd, st_select_lex *select_lex,
+			       select_subselect *result):
   assigned(0), executed(0), optimized(0), error(0)
 {
   DBUG_ENTER("Item_subselect::Item_subselect");
   DBUG_PRINT("subs", ("select_lex 0x%xl", (long) select_lex));
-  result= new select_subselect(this);
+  this->result= result;
   SELECT_LEX_UNIT *unit= select_lex->master_unit();
   unit->offset_limit_cnt= unit->global_parameters->offset_limit;
   unit->select_limit_cnt= unit->global_parameters->select_limit+
@@ -51,41 +52,15 @@ Item_subselect::Item_subselect(THD *thd, st_select_lex *select_lex):
     select_lex->options&= ~OPTION_FOUND_ROWS;
   join= new JOIN(thd, select_lex->item_list, select_lex->options, result);
   this->select_lex= select_lex;
-  maybe_null= 1;
+  assign_null();
   /*
     item value is NULL if select_subselect not changed this value 
     (i.e. some rows will be found returned)
   */
-  assign_null();
+  null_value= 1;
   DBUG_VOID_RETURN;
 }
 
-Item::Type Item_subselect::type() const 
-{
-  return SUBSELECT_ITEM;
-}
-
-double Item_subselect::val () 
-{
-  if (exec())
-    return 0;
-  return real_value;
-}
-
-longlong Item_subselect::val_int () 
-{
-  if (exec())
-    return 0;
-  return int_value;
-}
-
-String *Item_subselect::val_str (String *str) 
-{
-  if (exec() || null_value)
-    return 0;
-  return &str_value;
-}
-
 void Item_subselect::make_field (Send_field *tmp_field)
 {
   if (null_value)
@@ -110,7 +85,7 @@ bool Item_subselect::fix_fields(THD *thd,TABLE_LIST *tables)
     return 1;
   }
   // Is it one field subselect?
-  if (select_lex->item_list.elements != 1)
+  if (select_lex->item_list.elements > max_columns)
   {  
     my_printf_error(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL), MYF(0));
     return 1;
@@ -131,13 +106,14 @@ bool Item_subselect::fix_fields(THD *thd,TABLE_LIST *tables)
 
 int Item_subselect::exec()
 {
+  DBUG_ENTER("Item_subselect::exec");
   if (!optimized)
   {
     optimized=1;
     if (join->optimize())
     {
       executed= 1;
-      return (join->error?join->error:1);
+      DBUG_RETURN(join->error?join->error:1);
     }
   }
   if (join->select_lex->depended && executed)
@@ -145,7 +121,7 @@ int Item_subselect::exec()
     if (join->reinit())
     {
       error= 1;
-      return 1;
+      DBUG_RETURN(1);
     }
     assign_null();
     executed= assigned= 0;
@@ -157,7 +133,80 @@ int Item_subselect::exec()
     join->exec();
     join->thd->lex.select= save_select;
     executed= 1;
-    return join->error;
+    DBUG_RETURN(join->error);
   }
+  DBUG_RETURN(0);
+}
+
+inline table_map Item_subselect::used_tables() const
+{
+  return (table_map) select_lex->depended ? 1L : 0L; 
+}
+
+Item_singleval_subselect::Item_singleval_subselect(THD *thd,
+						   st_select_lex *select_lex):
+  Item_subselect(thd, select_lex, new select_singleval_subselect(this))
+{
+  max_columns= 1;
+  maybe_null= 1;
+}
+
+Item::Type Item_subselect::type() const 
+{
+  return SUBSELECT_ITEM;
+}
+
+double Item_singleval_subselect::val () 
+{
+  if (exec())
     return 0;
+  return real_value;
 }
+
+longlong Item_singleval_subselect::val_int () 
+{
+  if (exec())
+    return 0;
+  return int_value;
+}
+
+String *Item_singleval_subselect::val_str (String *str) 
+{
+  if (exec() || null_value)
+    return 0;
+  return &str_value;
+}
+
+Item_exists_subselect::Item_exists_subselect(THD *thd,
+					     st_select_lex *select_lex):
+  Item_subselect(thd, select_lex, new select_singleval_subselect(this))
+{
+  max_columns= UINT_MAX;
+  null_value= 0; //can't be NULL
+  maybe_null= 0; //can't be NULL
+  value= 0;
+  select_lex->select_limit= 1; // we need only 1 row to determinate existence
+}
+
+double Item_exists_subselect::val () 
+{
+  if (exec())
+    return 0;
+  return (double) value;
+}
+
+longlong Item_exists_subselect::val_int () 
+{
+  if (exec())
+    return 0;
+  return value;
+}
+
+String *Item_exists_subselect::val_str(String *str)
+{
+  if (exec())
+    return 0;
+  str->set(value);
+  return str;
+}
+

sql/item_subselect.h

@@ -24,42 +24,34 @@ struct st_select_lex;
 class JOIN;
 class select_subselect;
 
-/* simple (not depended of covered select ) subselect */
+/* base class for subselects */
 
 class Item_subselect :public Item
 {
 protected:
-  longlong int_value;
-  double real_value;
+  uint max_columns;
   my_bool assigned; /* value already assigned to subselect */
   my_bool executed; /* simple subselect is executed */
   my_bool optimized; /* simple subselect is optimized */
   my_bool error; /* error in query */
-  enum Item_result res_type;
 
   int exec();
-  void assign_null() 
+  virtual void assign_null() 
   {
     null_value= 1;
-    int_value= 0;
-    real_value= 0;
-    max_length= 4;
-    res_type= STRING_RESULT;
   }
 public:
   st_select_lex *select_lex;
   JOIN *join;
   select_subselect *result;
 
-  Item_subselect(THD *thd, st_select_lex *select_lex);
+  Item_subselect(THD *thd, st_select_lex *select_lex,
+		 select_subselect* result);
   Item_subselect(Item_subselect *item)
   {
     null_value= item->null_value;
-    int_value= item->int_value;
-    real_value= item->real_value;
-    max_length= item->max_length;
     decimals= item->decimals;
-    res_type= item->res_type;
+    max_columns= item->max_columns;
     assigned= item->assigned;
     executed= item->executed;
     select_lex= item->select_lex;
@@ -69,16 +61,75 @@ public:
     error= item->error;
   }
   enum Type type() const;
-  double val ();
-  longlong val_int ();
-  String *val_str (String *);
   bool is_null() { return null_value; }
   void make_field (Send_field *);
   bool fix_fields(THD *thd, TABLE_LIST *tables);
-  Item *new_item() { return new Item_subselect(this); }
-  enum Item_result result_type() const { return res_type; }
+  table_map used_tables() const;
 
   friend class select_subselect;
 };
 
 
+/* single value subselect */
+
+class Item_singleval_subselect :public Item_subselect
+{
+protected:
+  longlong int_value;
+  double real_value;
+  enum Item_result res_type;
+
+  virtual void assign_null() 
+  {
+    null_value= 1;
+    int_value= 0;
+    real_value= 0;
+    max_length= 4;
+    res_type= STRING_RESULT;
+  }
+public:
+  Item_singleval_subselect(THD *thd, st_select_lex *select_lex);
+  Item_singleval_subselect(Item_singleval_subselect *item):
+    Item_subselect(item)
+  {
+    int_value= item->int_value;
+    real_value= item->real_value;
+    max_length= item->max_length;
+    decimals= item->decimals;
+    res_type= item->res_type;
+  }
+  double val ();
+  longlong val_int ();
+  String *val_str (String *);
+  Item *new_item() { return new Item_singleval_subselect(this); }
+  enum Item_result result_type() const { return res_type; }
+
+  friend class select_singleval_subselect;
+};
+
+/* exists subselect */
+
+class Item_exists_subselect :public Item_subselect
+{
+protected:
+  longlong value;
+
+  virtual void assign_null() 
+  {
+    value= 0;
+  }
+public:
+  Item_exists_subselect(THD *thd, st_select_lex *select_lex);
+  Item_exists_subselect(Item_exists_subselect *item):
+    Item_subselect(item)
+  {
+    value= item->value;
+  }
+  Item *new_item() { return new Item_exists_subselect(this); }
+  enum Item_result result_type() const { return INT_RESULT;}
+  longlong val_int();
+  double val();
+  String *val_str(String*);
+
+  friend class select_exists_subselect;
+};

sql/sql_class.cc

@@ -763,7 +763,6 @@ void select_dump::send_error(uint errcode,const char *err)
   file= -1;
 }
 
-
 bool select_dump::send_eof()
 {
   int error=test(end_io_cache(&cache));
@@ -782,10 +781,11 @@ select_subselect::select_subselect(Item_subselect *item)
   this->item=item;
 }
 
-bool select_subselect::send_data(List<Item> &items)
+bool select_singleval_subselect::send_data(List<Item> &items)
 {
-  DBUG_ENTER("select_subselect::send_data");
-  if (item->assigned){
+  DBUG_ENTER("select_singleval_subselect::send_data");
+  Item_singleval_subselect *it= (Item_singleval_subselect *)item;
+  if (it->assigned){
     my_printf_error(ER_SUBSELECT_NO_1_ROW, ER(ER_SUBSELECT_NO_1_ROW), MYF(0));
     DBUG_RETURN(1);
   }
@@ -800,18 +800,33 @@ bool select_subselect::send_data(List<Item> &items)
     Following val() call have to be first, because function AVG() & STD()
     calculate value on it & determinate "is it NULL?".
   */
-  item->real_value= val_item->val();
-  if ((item->null_value= val_item->is_null()))
+  it->real_value= val_item->val();
+  if ((it->null_value= val_item->is_null()))
   {
-    item->assign_null();
+    it->assign_null();
   } else {
-    item->max_length= val_item->max_length;
-    item->decimals= val_item->decimals;
-    item->binary= val_item->binary;
-    val_item->val_str(&item->str_value);
-    item->int_value= val_item->val_int();
-    item->res_type= val_item->result_type();
-  }
-  item->assigned= 1;
+    it->max_length= val_item->max_length;
+    it->decimals= val_item->decimals;
+    it->binary= val_item->binary;
+    val_item->val_str(&it->str_value);
+    it->int_value= val_item->val_int();
+    it->res_type= val_item->result_type();
+  }
+  it->assigned= 1;
   DBUG_RETURN(0);
 }
+
+bool select_exists_subselect::send_data(List<Item> &items)
+{
+  DBUG_ENTER("select_exists_subselect::send_data");
+  Item_exists_subselect *it= (Item_exists_subselect *)item;
+  if (unit->offset_limit_cnt)
+  {				          // Using limit offset,count
+    unit->offset_limit_cnt--;
+    DBUG_RETURN(0);
+  }
+  it->value= 1;
+  it->assigned= 1;
+  DBUG_RETURN(0);
+}
+

sql/sql_class.h

@@ -712,19 +712,36 @@ class select_union :public select_result {
   bool flush();
 };
 
-/* Single value subselect interface class */
+/* Base subselect interface class */
 class select_subselect :public select_result
 {
+protected:
   Item_subselect *item;
 public:
   select_subselect(Item_subselect *item);
   bool send_fields(List<Item> &list, uint flag) { return 0; };
-  bool send_data(List<Item> &items);
+  bool send_data(List<Item> &items)=0;
   bool send_eof() { return 0; };
 
   friend class Ttem_subselect;
 };
 
+/* Single value subselect interface class */
+class select_singleval_subselect :public select_subselect
+{
+public:
+  select_singleval_subselect(Item_subselect *item):select_subselect(item){}
+  bool send_data(List<Item> &items);
+};
+
+/* EXISTS subselect interface class */
+class select_exists_subselect :public select_subselect
+{
+public:
+  select_exists_subselect(Item_subselect *item):select_subselect(item){}
+  bool send_data(List<Item> &items);
+};
+
 /* Structs used when sorting */
 
 typedef struct st_sort_field {

sql/sql_yacc.yy

@@ -548,7 +548,8 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 	literal text_literal insert_ident order_ident
 	simple_ident select_item2 expr opt_expr opt_else sum_expr in_sum_expr
 	table_wild opt_pad no_in_expr expr_expr simple_expr no_and_expr
-	using_list subselect subselect_init
+	using_list singleval_subselect singleval_subselect_init
+	exists_subselect exists_subselect_init
 
 %type <item_list>
 	expr_list udf_expr_list when_list ident_list ident_list_arg
@@ -1738,7 +1739,8 @@ simple_expr:
 	| NOT expr %prec NEG	{ $$= new Item_func_not($2); }
 	| '!' expr %prec NEG	{ $$= new Item_func_not($2); }
 	| '(' expr ')'		{ $$= $2; }
-	| subselect             { $$= $1; }
+	| EXISTS exists_subselect { $$= $2; }
+	| singleval_subselect   { $$= $1; }
 	| '{' ident expr '}'	{ $$= $3; }
         | MATCH ident_list_arg AGAINST '(' expr ')'
           { Select->ftfunc_list.push_back((Item_func_match *)
@@ -3918,17 +3920,30 @@ union_option:
   /* empty */ {}
   | ALL {Lex->union_option=1;};
 
-subselect:
-  subselect_start subselect_init
+singleval_subselect:
+  subselect_start singleval_subselect_init
   subselect_end
   {
     $$= $2;
   };
 
-subselect_init:
+singleval_subselect_init:
   select_init
   {
-    $$= new Item_subselect(current_thd, Lex->select);
+    $$= new Item_singleval_subselect(current_thd, Lex->select);
+  };
+
+exists_subselect:
+  subselect_start exists_subselect_init
+  subselect_end
+  {
+    $$= $2;
+  };
+
+exists_subselect_init:
+  select_init
+  {
+    $$= new Item_exists_subselect(current_thd, Lex->select);
   };
 
 subselect_start: