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.

1 files changed, 7 insertions, 7 deletions

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);