bk commit into 5.0 tree (igor:1.2347)

[igor]

Below is the list of changes that have just been committed into a local
5.0 repository of igor. When igor does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2006-12-12 11:53:09-08:00, igor@stripped +4 -0
  Merge olga.mysql.com:/home/igor/mysql-4.1-opt
  into  olga.mysql.com:/home/igor/mysql-5.0-opt
  MERGE: 1.1616.2867.27

  mysql-test/r/subselect.result@stripped, 2006-12-12 11:53:07-08:00, igor@stripped +0 -0
    Manual merge
    MERGE: 1.67.1.119

  mysql-test/t/subselect.test@stripped, 2006-12-12 11:53:07-08:00, igor@stripped +0 -0
    Manual merge
    MERGE: 1.58.1.105

  sql/item_subselect.cc@stripped, 2006-12-12 11:44:29-08:00, igor@stripped +0 -0
    Auto merged
    MERGE: 1.60.1.87

  sql/item_subselect.h@stripped, 2006-12-12 11:53:07-08:00, igor@stripped +1 -1
    Manual merge
    MERGE: 1.52.1.13

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	igor
# Host:	olga.mysql.com
# Root:	/home/igor/mysql-5.0-opt/RESYNC

--- 1.166/mysql-test/r/subselect.result	2006-12-12 11:53:15 -08:00
+++ 1.167/mysql-test/r/subselect.result	2006-12-12 11:53:15 -08:00
@@ -3033,6 +3033,19 @@
   `a` datetime default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1,t2,t3;
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (1), (2);
+SELECT a FROM t1 WHERE (SELECT 1 FROM DUAL WHERE 1=0) > 0;
+a
+SELECT a FROM t1 WHERE (SELECT 1 FROM DUAL WHERE 1=0) IS NULL;
+a
+1
+2
+EXPLAIN SELECT a FROM t1 WHERE (SELECT 1 FROM DUAL WHERE 1=0) IS NULL;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	
+2	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+DROP TABLE t1;
 create table t1 (df decimal(5,1));
 insert into t1 values(1.1);
 insert into t1 values(2.2);

--- 1.135/mysql-test/t/subselect.test	2006-12-12 11:53:15 -08:00
+++ 1.136/mysql-test/t/subselect.test	2006-12-12 11:53:15 -08:00
@@ -1988,6 +1988,18 @@
 
 DROP TABLE t1,t2,t3;
 
+#
+# Bug 24670: subquery witout tables but with a WHERE clause
+#
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (1), (2);
+
+SELECT a FROM t1 WHERE (SELECT 1 FROM DUAL WHERE 1=0) > 0;
+SELECT a FROM t1 WHERE (SELECT 1 FROM DUAL WHERE 1=0) IS NULL;
+EXPLAIN SELECT a FROM t1 WHERE (SELECT 1 FROM DUAL WHERE 1=0) IS NULL;
+
+DROP TABLE t1;
 # End of 4.1 tests
 
 #

--- 1.143/sql/item_subselect.cc	2006-12-12 11:53:15 -08:00
+++ 1.144/sql/item_subselect.cc	2006-12-12 11:53:15 -08:00
@@ -349,6 +349,7 @@
       */
       !(select_lex->item_list.head()->type() == FIELD_ITEM ||
 	select_lex->item_list.head()->type() == REF_ITEM) &&
+      !join->conds && !join->having &&
       /*
         switch off this optimization for prepare statement,
         because we do not rollback this changes
@@ -373,8 +374,6 @@
     */
     substitution->walk(&Item::remove_dependence_processor,
 		       (byte *) select_lex->outer_select());
-    /* SELECT without FROM clause can't have WHERE or HAVING clause */
-    DBUG_ASSERT(join->conds == 0 && join->having == 0);
     return RES_REDUCE;
   }
   return RES_OK;
@@ -2274,6 +2273,22 @@
 bool subselect_single_select_engine::no_tables()
 {
   return(select_lex->table_list.elements == 0);
+}
+
+
+/*
+  Check statically whether the subquery can return NULL
+
+  SINOPSYS
+    subselect_single_select_engine::may_be_null()
+
+  RETURN
+    FALSE  can guarantee that the subquery never return NULL
+    TRUE   otherwise
+*/
+bool subselect_single_select_engine::may_be_null()
+{
+  return ((no_tables() && !join->conds && !join->having) ? maybe_null : 1);
 }
 
 

--- 1.83/sql/item_subselect.h	2006-12-12 11:53:15 -08:00
+++ 1.84/sql/item_subselect.h	2006-12-12 11:53:15 -08:00
@@ -363,7 +363,7 @@
   enum Item_result type() { return res_type; }
   enum_field_types field_type() { return res_field_type; }
   virtual void exclude()= 0;
-  bool may_be_null() { return maybe_null; };
+  virtual bool may_be_null() { return maybe_null; };
   virtual table_map upper_select_const_tables()= 0;
   static table_map calc_const_tables(TABLE_LIST *);
   virtual void print(String *str)= 0;
@@ -400,6 +400,7 @@
   void print (String *str);
   bool change_result(Item_subselect *si, select_subselect *result);
   bool no_tables();
+  bool may_be_null();
   bool is_executed() const { return executed; }
   bool no_rows();
 };