Merge gshchepa.loc:/home/uchum/work/bk-trees/mysql-4.1-opt-27704

into  gshchepa.loc:/home/uchum/work/bk-trees/mysql-5.0-opt-27704


mysql-test/r/subselect.result:
  Auto merged
mysql-test/t/row.test:
  Auto merged
mysql-test/r/row.result:
  Test case updated for Bug#27704 (incorrect comparison
  of rows with NULL components).
sql/item_cmpfunc.cc:
  Bug#27704: incorrect comparison of rows with NULL components.
sql/item_cmpfunc.h:
  Bug#27704: incorrect comparison of rows with NULL components.
  Cosmetic fix.

1 files changed, 14 insertions, 4 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index f9844f6d36e..a2a68151b7a 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -811,8 +811,18 @@ int Arg_comparator::compare_row()
     if (owner->null_value)
     {
       // NULL was compared
-      if (owner->abort_on_null)
-        return -1; // We do not need correct NULL returning
+      switch (owner->functype()) {
+      case Item_func::NE_FUNC:
+        break; // NE never aborts on NULL even if abort_on_null is set
+      case Item_func::LT_FUNC:
+      case Item_func::LE_FUNC:
+      case Item_func::GT_FUNC:
+      case Item_func::GE_FUNC:
+        return -1; // <, <=, > and >= always fail on NULL
+      default: // EQ_FUNC
+        if (owner->abort_on_null)
+          return -1; // We do not need correct NULL returning
+      }
       was_null= 1;
       owner->null_value= 0;
       res= 0;  // continue comparison (maybe we will meet explicit difference)
@@ -823,8 +833,8 @@ int Arg_comparator::compare_row()
   if (was_null)
   {
     /*
-      There was NULL(s) in comparison in some parts, but there was not
-      explicit difference in other parts, so we have to return NULL
+      There was NULL(s) in comparison in some parts, but there was no
+      explicit difference in other parts, so we have to return NULL.
     */
     owner->null_value= 1;
     return -1;