create table t1(a integer) engine=innodb;
ERROR 42000: This table type requires a primary key
show warnings;
Level	Code	Message
Error	1173	This table type requires a primary key
create table t1(a integer unique key) engine=innodb;
ERROR 42000: This table type requires a primary key
show warnings;
Level	Code	Message
Error	1173	This table type requires a primary key
create table t1(a integer not null, b integer,
unique key(a,b)) engine=innodb;
ERROR 42000: This table type requires a primary key
show warnings;
Level	Code	Message
Error	1173	This table type requires a primary key
create table t1(a integer not null primary key) engine=innodb;
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `a` int(11) NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
show warnings;
Level	Code	Message
drop table t1;
create table t1(a integer not null unique key) engine=innodb;
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `a` int(11) NOT NULL,
  UNIQUE KEY `a` (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
show warnings;
Level	Code	Message
drop table t1;
set global innodb_force_primary_key = 0;
create table t1(a integer) engine=innodb;
show warnings;
Level	Code	Message
insert into t1 values (1),(2),(3);
set global innodb_force_primary_key = 1;
select * from t1;
a
1
2
3
create table t2(a integer) engine=innodb;
ERROR 42000: This table type requires a primary key
show warnings;
Level	Code	Message
Error	1173	This table type requires a primary key
drop table t1;
create table t1 (i int not null, key(i)) engine=innodb;
ERROR 42000: This table type requires a primary key
create table t1 (i int not null, unique key(i)) engine=innodb;
show warnings;
Level	Code	Message
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `i` int(11) NOT NULL,
  UNIQUE KEY `i` (`i`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
drop table t1;