1.1 tinyint说明
类型
长度
不指定时长度为
占用字节
范围
有符号
无符号
tinyint
3
4
1(8bit)
-128~127
-128~127
0~255
id tinyint(M) [UNSIGNED] [ZEROFILL]
字段名 字段类型(长度) [无符号] [前导填充]
unsigned：
01：tinyint(M)后面加上unsigned后,就是无符号（tinyint的范围就是0~255）
02：tinyint(M)后面不加上unsigned,就是有符号（tinyint的范围就是-128~127）
zerofill：
01：进行前导零填充
02：tinyint(M)加上zerofile后，同时也会把unsigned参数也带上(tinyint范围0~255)
1.2 实践检验
##创建chenliang库
mysql> create database if not exists chenliang;
Query OK, 1 row affected (0.03 sec)
mysql> show databases like "chenliang";
+----------------------+
| Database (chenliang) |
+----------------------+
| chenliang |
+----------------------+
1 row in set (0.03 sec)
##进入chenliang库
mysql> use chenliang;
Database changed
mysql> select database();
+------------+
| database() |
+------------+
| chenliang |
+------------+
1 row in set (0.01 sec)
测试一：测试字段加上UNSIGNED后情况下插入数据的情况
##创建test1测试表（这里指定了UNSIGNED，也就是无符号）
mysql> CREATE TABLE IF NOT EXISTS test1(
-> id tinyint(3) UNSIGNED
-> );
Query OK, 0 rows affected (0.06 sec)
mysql> desc test1;
+-------+----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------------------+------+-----+---------+-------+
| id | tinyint(3) unsigned | YES | | NULL | |
+-------+----------------------+------+-----+---------+-------+
1 row in set (0.03 sec)
****测试01：测试插入范围0~255的整数和走近255的整数
mysql> INSERT INTO test1 values(0); <==插入数值0，正常（没有超过范围）
Query OK, 1 row affected (0.06 sec)
mysql> INSERT INTO test1 values(255); <==插入数值255，正常（没有超过范围）
Query OK, 1 row affected (0.05 sec)
mysql> INSERT INTO test1 values(256); <=插入数值256,错误(超过了tinyint的范围)
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> select * from test1;
+------+
| id |
+------+
| 0 |
| 255 |
+------+
2 rows in set (0.00 sec)
***测试02：测试-128~127范围的数据是否能够正常插入
mysql> INSERT INTO test1 values(-1); <==插入负数，报错
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> INSERT INTO test1 values(-128); <==插入-128,报错
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> INSERT INTO test1 values(-129); <==插入-129,报错
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> select * from test1;
+-------+
| id |
+-------+
| 0 |
| 255 |
+-------+
2 rows in set (0.00 sec)
测试二：测试字段加ZEROFILL上后情况下插入数据的情况
##创建test2表，（这里指定了zerofill,也就是前导零填充）
mysql> CREATE TABLE IF NOT EXISTS test2(
-> id tinyint(3) ZEROFILL
-> );
Query OK, 0 rows affected (0.07 sec)
mysql> desc test2;
+-------+------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------------------------+------+-----+---------+-------+
| id | tinyint(3) unsigned zerofill | YES | | NULL | |
+-------+------------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)
^只指定unsigned，不会有zerofill
^只指定zerofill时，会带上unsigned
****测试01：测试插入范围0~255的整数和走近255的整数
mysql> INSERT INTO test2 values(0);
Query OK, 1 row affected (0.01 sec)
mysql> INSERT INTO test2 values(255);
Query OK, 1 row affected (0.08 sec)
mysql> INSERT INTO test2 values(256);
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> select * from test2;
+------+
| id |
+------+
| 000 |
| 255 |
+------+
2 rows in set (0.00 sec)
***测试02：测试-128~127范围的数据是否能够正常插入
mysql> INSERT INTO test2 values(-1);
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> INSERT INTO test2 values(-128);
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> INSERT INTO test2 values(-129);
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> select * from test2;
+------+
| id |
+------+
| 000 |
| 255 |
+------+
2 rows in set (0.00 sec)
测试一：测试字段不加unsigned 和ZEROFILL上后情况下插入数据的情况
##创建test3表（不加unsigned和zerofill）
mysql> CREATE TABLE test3(
-> id tinyint(3)
-> );
Query OK, 0 rows affected (0.06 sec)
mysql> desc test3;
+-------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| id | tinyint(3) | YES | | NULL | |
+-------+------------+------+-----+---------+-------+
1 row in set (0.01 sec)
****测试01：测试插入整数
mysql> INSERT INTO test3 values(0);
Query OK, 1 row affected (0.05 sec)
mysql> INSERT INTO test3 values(128);
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> select * from test3;
+------+
| id |
+------+
| 0 |
+------+
1 row in set (0.01 sec)
***测试02：测试插入负数
mysql> INSERT INTO test3 values(-1);
Query OK, 1 row affected (0.10 sec)
mysql> INSERT INTO test3 values(-128);
Query OK, 1 row affected (0.02 sec)
mysql> INSERT INTO test3 values(-129);
ERROR 1264 (22003): Out of range value for column 'id' at row 1
mysql> select * from test3;
+------+
| id |
+------+
| 0 |
| -1 |
| -128 |
+------+
3 rows in set (0.00 sec)
1.3 tinyint总结
格式：
id tinyint(M) [UNSIGNED] [ZEROFILL]
字段名 字段类型(长度) [无符号] [前导填充]
unsigned：
01：tinyint(M)后面加上unsigned后,就是无符号（tinyint的范围就是0~255）
02：tinyint(M)后面不加上unsigned,就是有符号（tinyint的范围就是-128~127）
zerofill：
01：进行前导零填充（插入数值1，表中显示的是001，因为tinyint的长度为3）
02：tinyint(M)加上zerofile后，同时也会把unsigned参数也带上(tinyint范围0~255)