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mysql数据库数值型之整型
1、 整型 整形 | 占用字节数 | 范围 | | tinyint | 1 | -128~127 | | smallint | 2 | -32768~32767 | | mediumint | 3 | -8388608~8388607 | | int | 4 | -2147483648~2147483647 | | bigint | 8 | -9223372036854775808~9223372036854775807 |
选择的范围尽可能小，范围越小占用资源越少 代码如下：
- mysql> create table stu1(
- -> id tinyint, # 范围要尽可能小，范围越小，占用空间越少
- -> name varchar(20)
- -> );
- Query OK, 0 rows affected (0.02 sec)
- -- 超出范围会报错
- mysql> insert into stu1 values (128,'tom');
- ERROR 1264 (22003): Out of range value for column 'id' at row 1
- mysql> create table stu2(
- -> id tinyint unsigned # 无符号整数
- -> );
- Query OK, 0 rows affected (0.02 sec)
- mysql> insert into stu2 values (128);
- Query OK, 1 row affected (0.00 sec)
- mysql> create table stu4(
- -> id int(5),
- -> num int(5) zerofill # 添加前导0,int(5)显示宽带是5
- -> );
- Query OK, 0 rows affected (0.05 sec)
- mysql> insert into stu4 values (12,12);
- Query OK, 1 row affected (0.00 sec)
- mysql> select * from stu4;
- +------+-------+
- | id | num |
- +------+-------+
- | 12 | 00012 |
- +------+-------+
- 1 row in set (0.00 sec)
1、范围要尽可能小，范围越小，占用空间越少
2、无符号整数是整数的两倍
3、整形支持显示宽度，显示宽带是最小的显示位数，必须结合zerofill才起作用
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发表于 2022-11-27 18:24:29
