Problem:-
In myisam engine. If we run a query which is 
creating a table with select statement on a function statement, which 
return null as one of its column result in select query.Mysql deamon crashes.

If we are not able to generate the problem we have to run this query few times.

Analysis:-

If we have a null-constant in our select query, we are treating it as a binary 
type field, in both innodb and myisam engine.

mysql> create table `t1` select null as a;

mysql> show create table t1;
+-------+-----------------------
| Table | Create Table          
+-------+-----------------------
| t1    | CREATE TABLE `t1` (
  `a` binary(0) DEFAULT NULL
) ENGINE=MYISAM DEFAULT CHARSET=latin1 |
+-------+---------------------------------

If we have a null returning function in our select query, we are treating it as
null type field in myisam and giving error in innodb.
For example:-

mysql> Create table t1 engine=myisam
select coalesce(null);


mysql> show create table t1;
+-------+----------------------------------
| Table | Create Table                     
+-------+----------------------------------
| t1    | CREATE TABLE `t1` (
  `a` null DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+-------+----------------------------------

which is creating a problem.

Solution:-

Instead of creating a field type of null, now we are creating a binary of 
length zero.