MySQL一个语句查出各种整形占用字节数及最大最小值的实例

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