MySQL使用一个语句就可以查出各种整形占用字节数及最大最小值的示例代码

select 'bigint unsigned' as type ,'8' as bytes ,~0 as max_num,0 as min_num union
select 'int unsigned','4',~0>>32,0 union
select 'mediumint unsigned','3',~0>>40,0 union
select 'smallint unsigned','2',~0>>48,0 union
select 'tinyint unsigned','1',~0>>56,0 union
select 'signed bigint','8',~0>>1,-(1<<63) union
select 'signed int','4',~0>>33,-(1<<31) union
select 'signed mediumint','3',~0>>41,-(1<<23) union
select 'signed smallint','2',~0>>49,-(1<<15) union
select 'signed tinyint','1',~0>>57,-(1<<7);

+--------------------+-------+----------------------+----------------------+
| type    | bytes | max_num    | min_num    |
+--------------------+-------+----------------------+----------------------+
| bigint unsigned | 8  | 18446744073709551615 |     0 |
| int unsigned  | 4  |   4294967295 |     0 |
| mediumint unsigned | 3  |    16777215 |     0 |
| smallint unsigned | 2  |    65535 |     0 |
| tinyint unsigned | 1  |     255 |     0 |
| signed bigint  | 8  | 9223372036854775807 | -9223372036854775808 |
| signed int   | 4  |   2147483647 |   -2147483648 |
| signed mediumint | 3  |    8388607 |    -8388608 |
| signed smallint | 2  |    32767 |    -32768 |
| signed tinyint  | 1  |     127 |     -128 |
+--------------------+-------+----------------------+----------------------+
rows in set (0.00 sec)