1create table t1 (a int);
2alter table mysql.column_stats rename to mysql.column_stats1;
3flush tables;
4alter table t1 change a b varchar(100);
5show create table t1;
6Table	Create Table
7t1	CREATE TABLE `t1` (
8  `b` varchar(100) DEFAULT NULL
9) ENGINE=MyISAM DEFAULT CHARSET=latin1
10alter table mysql.column_stats1 rename to mysql.column_stats;
11drop table t1;
12