fix (bug #11964: ALTER TABLE gives wrong error message with sql-mode TRADITIONAL (timestamp)).

mysql-test/r/strict.result

@@ -1258,3 +1258,24 @@ select * from t1;
 d
 2000-10-01
 drop table t1;
+set @@sql_mode='traditional';
+create table t1(a int, b timestamp);
+alter table t1 add primary key(a);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) NOT NULL default '0',
+  `b` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
+  PRIMARY KEY  (`a`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
+create table t1(a int, b timestamp default 20050102030405);
+alter table t1 add primary key(a);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) NOT NULL default '0',
+  `b` timestamp NOT NULL default '2005-01-02 03:04:05',
+  PRIMARY KEY  (`a`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;

mysql-test/t/strict.test

@@ -1118,3 +1118,17 @@ insert into t1 values ('2000-10-01');
 update t1 set d = 1100;
 select * from t1;
 drop table t1;
+
+#
+# Bug #11964: alter table with timestamp field
+#
+
+set @@sql_mode='traditional';
+create table t1(a int, b timestamp);
+alter table t1 add primary key(a);
+show create table t1;
+drop table t1;
+create table t1(a int, b timestamp default 20050102030405);
+alter table t1 add primary key(a);
+show create table t1;
+drop table t1;

sql/field.cc

@@ -8462,7 +8462,10 @@ create_field::create_field(Field *old_field,Field *orig_field)
   def=0;
   if (!(flags & (NO_DEFAULT_VALUE_FLAG | BLOB_FLAG)) &&
       !old_field->is_real_null() &&
-      old_field->ptr && orig_field)
+      old_field->ptr && orig_field &&
+      (sql_type != FIELD_TYPE_TIMESTAMP ||                /* set def only if */
+       old_field->table->timestamp_field != old_field ||  /* timestamp field */ 
+       unireg_check == Field::TIMESTAMP_UN_FIELD))        /* has default val */
   {
     char buff[MAX_FIELD_WIDTH],*pos;
     String tmp(buff,sizeof(buff), charset), *res;