drop table if exists t1,t2;
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 'a'
show binlog events;
Log_name	Pos	Event_type	Server_id	End_log_pos	Info
master-bin.000001	4	Format_desc	1	103	Server ver: VERSION, Binlog ver: 4
master-bin.000001	103	Table_map	1	142	table_id: # (test.t1)
master-bin.000001	142	Write_rows	1	176	table_id: # flags: STMT_END_F
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 'a'
show binlog events;
Log_name	Pos	Event_type	Server_id	End_log_pos	Info
master-bin.000001	4	Format_desc	1	103	Server ver: VERSION, Binlog ver: 4
drop table t1;