诛仙合欢一尘装备图片:[MySQL] mysql int(1) tinyint(1)有什么区别

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 mysql int(1) tinyint(1)有什么区别?
我指定了字段长度,类型还有意义吗? Reply:mysql 中int(1)和tinyint(1)中的1只是指定显示长度,并不表示存储长度,只有字段指定zerofill是有用
如int(3),如果实际值是2,如果列指定了zerofill,查询结果就是002,左边用0来填充。 TINYINT[(M)] [UNSIGNED] [ZEROFILL] 

A very small integer. The signed range is -128 to 127. The unsigned range is 0 to 255. 

INT[(M)] [UNSIGNED] [ZEROFILL] 

A normal-size integer. The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295. 


位数限制基本没有意义。

mysql> create table testint(id int(1), col2 tinyint(1));
Query OK, 0 rows affected (0.06 sec)

mysql> insert into testint values(256, 257);
Query OK, 1 row affected, 1 warning (0.03 sec)

mysql> select * from testint;
+------+------+
| id | col2 |
+------+------+
| 256 | 127 |
+------+------+
1 row in set (0.02 sec)

mysql> insert into testint values(336, 257);
Query OK, 1 row affected, 1 warning (0.02 sec)

mysql> select * from testint;
+------+------+
| id | col2 |
+------+------+
| 256 | 127 |
| 336 | 127 |
+------+------+
2 rows in set (0.00 sec)

mysql> insert into testint values(336, 255);
Query OK, 1 row affected, 1 warning (0.03 sec)

mysql> select * from testint;
+------+------+
| id | col2 |
+------+------+
| 256 | 127 |
| 336 | 127 |
| 336 | 127 |
+------+------+
3 rows in set (0.00 sec)

mysql>

关注一下上边的warning提示。。。。
----------------------------mysql   中   真,假   这样的数据应该用什么数据类型?reply:tinyint(1)