drop table if exists t1;
SET SQL_WARNINGS=1;
create table t1 (this int unsigned);
insert into t1 values (1);
insert into t1 values (-1);
Warnings:
Warning	1264	Out of range value for column 'this' at row 1
insert into t1 values ('5000000000');
Warnings:
Warning	1264	Out of range value for column 'this' at row 1
select * from t1;
this
1
0
4294967295
drop table t1;
create table t1 (a bigint unsigned, b mediumint unsigned);
insert t1 values (1,2),(0xffffffffffffffff,0xffffff);
select coalesce(a,b), coalesce(b,a) from t1;
coalesce(a,b)	coalesce(b,a)
1	2
18446744073709551615	16777215
create table t2 as select a from t1 union select b from t1;
show create table t2;
Table	Create Table
t2	CREATE TABLE `t2` (
  `a` bigint(20) unsigned DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
select * from t2;
a
1
18446744073709551615
2
16777215
drop table t1, t2;