BUG 11104 (same as changeset 1.1891 on the 5.0 tree, but realised this

needed to be fixed in earlier versions)
Fixed the iteration of how substrings are handled with negative indexes in 
SUBSTRING_INDEX

1 files changed, 14 insertions, 2 deletions

diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index 930014de771..f070382e5c1 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -1084,11 +1084,23 @@ String *Item_func_substr_index::val_str(String *str)
       }
     }
     else
-    {					// Start counting at end
-      for (offset=res->length() ; ; offset-=delimeter_length-1)
+    {
+      /*
+        Negative index, start counting at the end
+      */
+      for (offset=res->length(); offset ;)
       {
+        /* 
+          this call will result in finding the position pointing to one 
+          address space less than where the found substring is located
+          in res
+        */
 	if ((int) (offset=res->strrstr(*delimeter,offset)) < 0)
 	  return res;			// Didn't find, return org string
+        /*
+          At this point, we've searched for the substring
+          the number of times as supplied by the index value
+        */
 	if (!++count)
 	{
 	  offset+=delimeter_length;