直接上码：
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 |
+--------------------+-------+----------------------+----------------------+
10 rows in set (0.00 sec)
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