--echo #
--echo # BUG#6236 - ALTER TABLE MODIFY should set implicit NOT NULL on PK columns
--echo #
create table t1 ( a varchar(10) not null primary key ) engine=myisam;
create table t2 ( a varchar(10) not null primary key ) engine=merge union=(t1);
flush tables;
alter table t1 modify a varchar(10);
show create table t2;
flush tables;
alter table t1 modify a varchar(10) not null;
show create table t2;
drop table if exists t1, t2;