Fixed that NULL and 0 returns 0 instead of NULL

This is coded to not cause a speed impact on top level AND expressions where we don't care if an AND expression returns 0 or NULL


mysql-test/r/bdb.result:
  Fix results after serges last patch
mysql-test/r/innodb.result:
  Fix results after serges last patch
mysql-test/r/null.result:
  Update for new AND handling of NULL
scripts/mysqld_safe.sh:
  Fix 'isroot' test to work even if user is not root
sql/item.h:
  Fixed that NULL and 0 returns 0 instead of NULL
sql/item_cmpfunc.cc:
  Fixed that NULL and 0 returns 0 instead of NULL
sql/item_cmpfunc.h:
  Fixed that NULL and 0 returns 0 instead of NULL
sql/sql_base.cc:
  Fixed that NULL and 0 returns 0 instead of NULL
sql/sql_parse.cc:
  Fixed that NULL and 0 returns 0 instead of NULL
sql/sql_select.cc:
  Fixed that NULL and 0 returns 0 instead of NULL
sql/sql_yacc.yy:
  Fixed that NULL and 0 returns 0 instead of NULL

1 files changed, 9 insertions, 5 deletions

diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 086a0a561a0..eb2d2ace467 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -3324,12 +3324,16 @@ static bool create_total_list(THD *thd, LEX *lex, TABLE_LIST **result)
 
 void add_join_on(TABLE_LIST *b,Item *expr)
 {
-  if (!b->on_expr)
-    b->on_expr=expr;
-  else
+  if (expr)
   {
-    // This only happens if you have both a right and left join
-    b->on_expr=new Item_cond_and(b->on_expr,expr);
+    if (!b->on_expr)
+      b->on_expr=expr;
+    else
+    {
+      // This only happens if you have both a right and left join
+      b->on_expr=new Item_cond_and(b->on_expr,expr);
+    }
+    b->on_expr->top_level_item();
   }
 }