USE test;
create table p(v varchar(20), i int, primary key(v,i)) engine=innodb character set = utf8;
create table c(k int primary key, v varchar(20), i int, foreign key(v,i) references p(v,i)) engine=innodb character set = utf8;
insert into p values (_utf32 0x000004100000041100000412, 1);
insert into c values (1, _utf32 0x000004100000041100000412, 1);
SELECT * FROM test.p;
v	i
???	1
SELECT * FROM test.c;
k	v	i
1	???	1
SELECT * FROM test.p;
v	i
???	1
SELECT * FROM test.c;
k	v	i
1	???	1
DROP TABLE c;
DROP TABLE p;