Proposed bugfix for #717

Current table is placed into read_tables set of the current join_tab->select
so get_mm_parts function thinks that current table's record is read and
tries to calculate WHERE condition with the fields of the record.
Result of these calculations is unpredictable.
Looks funny - outcome of the SELECT depends on the queries executed before.

Anyway i think we should have testcase on this part of the code.


mysql-test/r/sel000001.result:
  appropriate result added
mysql-test/t/sel000001.test:
  testcase added
sql/sql_select.cc:
  I think we should count current table out of read_tables set

mysql-test/r/sel000001.result

@@ -5,3 +5,17 @@ SELECT s, id FROM t1 WHERE s = 'mouse';
 s	id
 mouse	3
 drop table t1;
+CREATE TABLE t1 (
+node int(11) NOT NULL default '0',
+maxchild int(11) NOT NULL default '0',
+PRIMARY KEY  (`node`)
+);
+INSERT INTO t1 (node, maxchild) VALUES (4,4),(5,5),(1,244);
+SELECT * FROM t1 g1, t1 g2 
+WHERE g1.node <= g2.node and g2.node <= g1.maxchild and g2.node = g2.maxchild;
+node	maxchild	node	maxchild
+4	4	4	4
+5	5	5	5
+1	244	4	4
+1	244	5	5
+DROP TABLE t1;

mysql-test/t/sel000001.test

@@ -16,3 +16,16 @@ CREATE TABLE t1 (s CHAR(20) PRIMARY KEY, id INT);
 INSERT INTO t1 VALUES ('cat', 1), ('mouse', 3), ('dog', 2), ('snake', 77);
 SELECT s, id FROM t1 WHERE s = 'mouse';
 drop table t1;
+
+#
+#test for bug #717
+#
+CREATE TABLE t1 (
+  node int(11) NOT NULL default '0',
+  maxchild int(11) NOT NULL default '0',
+  PRIMARY KEY  (`node`)
+);
+INSERT INTO t1 (node, maxchild) VALUES (4,4),(5,5),(1,244);
+SELECT * FROM t1 g1, t1 g2 
+ WHERE g1.node <= g2.node and g2.node <= g1.maxchild and g2.node = g2.maxchild;
+DROP TABLE t1;

sql/sql_select.cc

@@ -2683,7 +2683,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
 			      (select->quick &&
 			       (select->quick->records >= 100L)))) ?
 	      2 : 1;
-	    sel->read_tables= used_tables;
+	    sel->read_tables= used_tables & ~current_map;
 	  }
 	  if (i != join->const_tables && tab->use_quick != 2)
 	  {					/* Read with cache */