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'
include/show_binlog_events.inc
Log_name	Pos	Event_type	Server_id	End_log_pos	Info
binlog.000001	#	Query	#	#	BEGIN
binlog.000001	#	Table_map	#	#	table_id: # (test.t1)
binlog.000001	#	Write_rows	#	#	table_id: # flags: STMT_END_F
binlog.000001	#	Query	#	#	COMMIT
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'
include/show_binlog_events.inc
Log_name	Pos	Event_type	Server_id	End_log_pos	Info
drop table t1;
drop table if exists t2;
Warnings:
Note	1051	Unknown table 'test.t2'