create table t1(a int, unique(a));
insert into t1 values(2);
create table t2(a int);
insert into t2 values(1),(2);
reset master;
insert into t1 select * from t2;
ERROR 23000: Duplicate entry '2' for key 1
show binlog events;
Log_name	Pos	Event_type	Server_id	Orig_log_pos	Info
master-bin.000001	4	Start	1	4	Server ver: VERSION, Binlog ver: 3
master-bin.000001	79	Query	1	79	use `test`; insert into t1 select * from t2
select * from t1;
a
1
2
drop table t1, t2;
create table t1(a int);
insert into t1 values(1),(1);
reset master;
create table t2(unique(a)) select a from t1;
ERROR 23000: Duplicate entry '1' for key 1
show binlog events;
Log_name	Pos	Event_type	Server_id	Orig_log_pos	Info
master-bin.000001	4	Start	1	4	Server ver: VERSION, Binlog ver: 3
drop table t1;
