1 files changed, 26 insertions, 5 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index d430d0d3c23..9443a2949d8 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -614,19 +614,38 @@ int Arg_comparator::compare_e_int_diff_signedness()
 int Arg_comparator::compare_row()
 {
   int res= 0;
+  bool was_null= 0;
   (*a)->bring_value();
   (*b)->bring_value();
   uint n= (*a)->cols();
   for (uint i= 0; i<n; i++)
   {
-    if ((res= comparators[i].compare()))
-      return res;
+    res= comparators[i].compare();
     if (owner->null_value)
-      return -1;
+    {
+      // NULL was compared
+      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)
+    }
+    else if (res)
+      return res;
   }
-  return res;
+  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
+    */
+    owner->null_value= 1;
+    return -1;
+  }
+  return 0;
 }
 
+
 int Arg_comparator::compare_e_row()
 {
   (*a)->bring_value();
@@ -1903,6 +1922,8 @@ in_row::~in_row()
 byte *in_row::get_value(Item *item)
 {
   tmp.store_value(item);
+  if (item->is_null())
+    return 0;
   return (byte *)&tmp;
 }
 
@@ -2791,7 +2812,7 @@ bool Item_func_like::fix_fields(THD *thd, Item **ref)
     /* If we are on execution stage */
     String *escape_str= escape_item->val_str(&tmp_value1);
     escape= escape_str ? *(escape_str->ptr()) : '\\';
- 
+
     /*
       We could also do boyer-more for non-const items, but as we would have to
       recompute the tables for each row it's not worth it.