A few problems were found in the fix for bug 43668:
1) Comparison of the YEAR column with NULL always returned TRUE;
2) Comparison of the YEAR column with constants always returned
unpredictable result;
3) Unnecessary conversion warnings when comparing a non-integer
constant with a NULL value in the YEAR column;
The problems described above have been resolved with an
exception: zero (i.e. invalid) YEAR column value comparison
with 00 or 2000 still fail (it is not a regression and it was
not a regression), so MIN/MAX on YEAR column containing zero
value still fail.
mysql-test/r/type_year.result:
Test case for bug #49480.
mysql-test/t/type_year.test:
Test case for bug #49480.
sql/item_cmpfunc.cc:
- The get_year_value() function has been modified to make its
return value compatible with the get_datetime_value() return
value (i.e. to convert numeric values into the YYYY0000000000
(YYYY-00-00 00:00:00) form.
- The Arg_comparator::set_cmp_func method has been modified to
use the get_year_value function if get_datetime_value() is not
applicable.
From now only 2 cases have a special processing there:
* both comparing items have MYSQL_TYPE_YEAR field type
or
* one item have is MYSQL_TYPE_YEAR and other one is
is_datetime()-compliant.
- New helper function try_year_cmp_func() has been
added for the better code readability to call from
Arg_comparator::set_cmp_func().
- The Arg_comparator::compare_year method has been removed
since get_year_value() is compatible with the old
Arg_comparator::compare_datetime method that doesn't have
problems #1-#3 (see whole patch entry commentary).
sql/item_cmpfunc.h:
- New helper function try_year_cmp_func() has been
added for the better code readability to call from
Arg_comparator::set_cmp_func().
- Unnecessary Arg_comparator::year_as_datetime and
Arg_comparator::compare_year() declarations have been
removed.
