Fix for Bug#34274: Invalid handling of 'DEFAULT 0'

for YEAR data type.

The problem was that for some unknown reason 0 was not allowed
as a default value for YEAR data type. That was coded before BK.
However the Manual does not say a word about such a limitation.
Also, it looks inconsistent with other data types.

The fix is to allow 0 as a default value.

mysql-test/r/create.result

@@ -1847,4 +1847,45 @@ DROP TABLE t3;
 
 # -- End of Bug#18834.
 
+# --
+# -- Bug#34274: Invalid handling of 'DEFAULT 0' for YEAR data type.
+# --
+
+DROP TABLE IF EXISTS t1;
+
+CREATE TABLE t1(c1 YEAR DEFAULT 2008, c2 YEAR DEFAULT 0);
+
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` year(4) DEFAULT '2008',
+  `c2` year(4) DEFAULT '0000'
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+
+INSERT INTO t1 VALUES();
+
+SELECT * FROM t1;
+c1	c2
+2008	0000
+
+ALTER TABLE t1 MODIFY c1 YEAR DEFAULT 0;
+
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` year(4) DEFAULT '0000',
+  `c2` year(4) DEFAULT '0000'
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+
+INSERT INTO t1 VALUES();
+
+SELECT * FROM t1;
+c1	c2
+2008	0000
+0000	0000
+
+DROP TABLE t1;
+
+# -- End of Bug#34274
+
 End of 5.1 tests

mysql-test/t/create.test

@@ -1365,6 +1365,8 @@ create table t1 like information_schema.character_sets;
 show create table t1;
 drop table t1;
 
+###########################################################################
+
 --echo
 --echo # --
 --echo # -- Bug#21380: DEFAULT definition not always transfered by CREATE
@@ -1407,8 +1409,10 @@ DROP TABLE t2;
 
 --echo
 --echo # -- End of test case for Bug#21380.
---echo
 
+###########################################################################
+
+--echo
 --echo # --
 --echo # -- Bug#18834: ALTER TABLE ADD INDEX on table with two timestamp fields
 --echo # --
@@ -1471,6 +1475,50 @@ DROP TABLE t3;
 
 --echo
 --echo # -- End of Bug#18834.
+
+###########################################################################
+
+--echo
+--echo # --
+--echo # -- Bug#34274: Invalid handling of 'DEFAULT 0' for YEAR data type.
+--echo # --
+--echo
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+--echo
+CREATE TABLE t1(c1 YEAR DEFAULT 2008, c2 YEAR DEFAULT 0);
+
+--echo
+SHOW CREATE TABLE t1;
+
+--echo
+INSERT INTO t1 VALUES();
+
+--echo
+SELECT * FROM t1;
+
+--echo
+ALTER TABLE t1 MODIFY c1 YEAR DEFAULT 0;
+
+--echo
+SHOW CREATE TABLE t1;
+
 --echo
+INSERT INTO t1 VALUES();
 
+--echo
+SELECT * FROM t1;
+
+--echo
+DROP TABLE t1;
+
+--echo
+--echo # -- End of Bug#34274
+
+###########################################################################
+
+--echo
 --echo End of 5.1 tests

sql/unireg.cc

@@ -979,9 +979,7 @@ static bool make_empty_rec(THD *thd, File file,enum legacy_db_type table_type,
 
     type= (Field::utype) MTYP_TYPENR(field->unireg_check);
 
-    if (field->def &&
-	(regfield->real_type() != MYSQL_TYPE_YEAR ||
-	 field->def->val_int() != 0))
+    if (field->def)
     {
       int res= field->def->save_in_field(regfield, 1);
       /* If not ok or warning of level 'note' */