MDEV-15262 Wrong results for SELECT..WHERE non_indexed_datetime_column=indexed_time_column

1 files changed, 7 insertions, 0 deletions

diff --git a/sql/field.cc b/sql/field.cc
index c36fff06a07..a9a7d54929b 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -5330,6 +5330,13 @@ static void calc_datetime_days_diff(MYSQL_TIME *ltime, long days)
                            ltime->second) * 1000000LL +
                            ltime->second_part);
     unpack_time(timediff, ltime);
+    /*
+      unpack_time() broke down hours into ltime members hour,day,month.
+      Mix them back to ltime->hour using the same factors
+      that pack_time()/unpack_time() use (i.e. 32 for month).
+    */
+    ltime->hour+= (ltime->month * 32 + ltime->day) * 24;
+    ltime->month= ltime->day= 0;
   }
   ltime->time_type= MYSQL_TIMESTAMP_TIME;
 }