From d096079d330f77eebd3c3abef04236a9a4a08d7b Mon Sep 17 00:00:00 2001
From: "Tatiana A. Nurnberg" <azundris@mysql.com>
Date: Wed, 26 Nov 2008 09:28:17 +0100
Subject: Bug#37553: MySql Error Compare TimeDiff & Time

We pretended that TIMEDIFF() would always return positive results;
this gave strange results in comparisons of the TIMEDIFF(low,hi)<TIME(0)
type that rendered a negative result, but still gave false in comparison.
We also inadvertantly dropped the sign when converting times to
decimal.

CAST(time AS DECIMAL) handles signs of the times correctly.
TIMEDIFF() marked up as signed. Time/date comparison code switched to
signed for clarity.

mysql-test/r/func_sapdb.result:
  show that time-related comparisons work with negative
  time values now.
  show that converting time to DECIMAL no longer drops sign.
mysql-test/t/func_sapdb.test:
  show that time-related comparisons work with negative
  time values now.
  show that converting time to DECIMAL no longer drops sign.
sql/item_cmpfunc.cc:
  signed returns
sql/item_cmpfunc.h:
  signed now (time/date < > =)
sql/item_func.cc:
  signed now
sql/item_timefunc.h:
  Functions such as TIMEDIFF() return signed results!
  The file-comments pretended we were doing that all along, anyway...
sql/my_decimal.cc:
  heed sign when converting time to my_decimal;
  times may actually be negative!
  Needed for SELECT CAST(time('-73:42:12') AS DECIMAL);
sql/mysql_priv.h:
  using signed for dates and times now
---
 sql/item_cmpfunc.cc | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

(limited to 'sql/item_cmpfunc.cc')

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 4bfae376acc..3b1d18b4252 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -745,11 +745,11 @@ Arg_comparator::can_compare_as_dates(Item *a, Item *b, ulonglong *const_value)
     obtained value
 */
 
-ulonglong
+longlong
 get_time_value(THD *thd, Item ***item_arg, Item **cache_arg,
                Item *warn_item, bool *is_null)
 {
-  ulonglong value;
+  longlong value;
   Item *item= **item_arg;
   MYSQL_TIME ltime;
 
@@ -761,7 +761,7 @@ get_time_value(THD *thd, Item ***item_arg, Item **cache_arg,
   else
   {
     *is_null= item->get_time(&ltime);
-    value= !*is_null ? TIME_to_ulonglong_datetime(&ltime) : 0;
+    value= !*is_null ? (longlong) TIME_to_ulonglong_datetime(&ltime) : 0;
   }
   /*
     Do not cache GET_USER_VAR() function as its const_item() may return TRUE
@@ -886,11 +886,11 @@ void Arg_comparator::set_datetime_cmp_func(Item **a1, Item **b1)
     obtained value
 */
 
-ulonglong
+longlong
 get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
                    Item *warn_item, bool *is_null)
 {
-  ulonglong value= 0;
+  longlong value= 0;
   String buf, *str= 0;
   Item *item= **item_arg;
 
@@ -925,7 +925,7 @@ get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
     enum_field_types f_type= warn_item->field_type();
     timestamp_type t_type= f_type ==
       MYSQL_TYPE_DATE ? MYSQL_TIMESTAMP_DATE : MYSQL_TIMESTAMP_DATETIME;
-    value= get_date_from_str(thd, str, t_type, warn_item->name, &error);
+    value= (longlong) get_date_from_str(thd, str, t_type, warn_item->name, &error);
     /*
       If str did not contain a valid date according to the current
       SQL_MODE, get_date_from_str() has already thrown a warning,
@@ -979,7 +979,7 @@ get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
 int Arg_comparator::compare_datetime()
 {
   bool a_is_null, b_is_null;
-  ulonglong a_value, b_value;
+  longlong a_value, b_value;
 
   /* Get DATE/DATETIME/TIME value of the 'a' item. */
   a_value= (*get_value_func)(thd, &a, &a_cache, *b, &a_is_null);
-- 
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