mysql中整数数据类型tinyint详解

#### 格式
id       tinyint(M)                 [unsigned]     [zerofill]
字段名  数据类型(显示长度,不指定指定)     无符号          无符号且前导零填充

#### 关于tinyint最大数值是怎样得来的
tinyint占用1字节,1字节占用8位，经过换算(2的8次方减1)就是255;

#### 关于加上unsigned后的说明
加上unsigned属性后就是无符号(范围是0~255的整数,因为是整数,不会有符号"-",所以就是无符号)

#### 关于加上zerofill后的说明
zerofill属性会把unsigned属性也给带上,这样就是无符号（范围是0~255，显示长度就是3），同时还会
进行前导零填充（没有达到显示长度的数值，例如：你插入1，显示的是001）。

#### 不加unsigned和zerofill的说明
字段后面不加上这两个属性中的任何一个,就表示是有符号(范围是-128~127,因为有符号"-",所有是有符号)。

#### 数据库版本和默认的存储引擎
mysql> select @@version,@@default_storage_engine;
+------------+--------------------------+
| @@version  | @@default_storage_engine |
+------------+--------------------------+
| 5.7.28-log | InnoDB                   |
+------------+--------------------------+
1 row in set (0.00 sec)
 
 
#### 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,并查看是否成功进入到库下面
mysql> use chenliang;
Database changed
 
mysql> select database();
+------------+
| database() |
+------------+
| chenliang  |
+------------+
1 row in set (0.01 sec)


#### 查看事务是否自动提交
mysql> select @@global.autocommit;
+---------------------+
| @@global.autocommit |
+---------------------+
|                   1 |
+---------------------+
1 row in set (0.00 sec)

#### 设置会话模式下的sql_mode中包含strict_trans_tables
mysql> set session sql_mode="STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
Query OK, 0 rows affected (0.00 sec)
 
mysql> select @@sql_mode\G
*************************** 1. row ***************************
@@sql_mode: STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
1 row in set (0.00 sec)


#### 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 UNSIGNED
    -> )engine=innodb character set utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.06 sec)
 　 
 　 ## id字段类型是tinyint unsigned,范围就是0~255,其长度是3;因为255的长度是3;


#### 查看test1表的表结构
mysql> desc test1;
+-------+---------------------+------+-----+---------+-------+
| Field | Type                | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+-------+
| id    | tinyint(3) unsigned | YES  |     | NULL    |       |
+-------+---------------------+------+-----+---------+-------+
1 row in set (0.03 sec)


#### 测试插入范围0~255范围整数和不在该范围内的整数
mysql> insert into test1 values(-1);   # 插入数值-1,错误(不在0~255范围内)
ERROR 1264 (22003): Out of range value for column 'id' at row 1
 
mysql> insert into test1 values(0);    # 插入数值0,正常(在0~255范围内)
Query OK, 1 row affected (0.06 sec)
 
mysql> insert into test1 values(255);  # 插入数值255,正常(在0~255范围内)
Query OK, 1 row affected (0.05 sec)
 
mysql> insert into test1 values(256);  # 插入数值256,错误(不在0~255范围内)
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)

#### 设置会话模式下sql_mode中不包含strit_trans_tables变量
mysql> set session sql_mode="NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select @@sql_mode\G
*************************** 1. row ***************************
@@sql_mode: NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
1 row in set (0.00 sec)



#### 创建test11表（这里指定了UNSIGNED，也就是无符号）
mysql> create table if not exists test11(
    -> id tinyint unsigned
    -> )engine=innodb character set utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.00 sec)
 　## id字段类型是tinyint unsigned,范围就是0~255,其长度是3;因为255的长度是3;



#### 查看test11表的表结构
mysql> desc test11;
+-------+---------------------+------+-----+---------+-------+
| Field | Type                | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+-------+
| id    | tinyint(3) unsigned | YES  |     | NULL    |       |
+-------+---------------------+------+-----+---------+-------+
1 row in set (0.00 sec)



#### 测试插入范围0~255范围整数和不在该范围内的整数
mysql> insert into test11(id) values(-1);
Query OK, 1 row affected, 1 warning (0.00 sec)
　　 ## 不在范围内,插入没有报错(因为sql_mode中没有开启严格模式)
　　 ## 插入到表中的数据不是-1,而是0
 
mysql> insert into test11(id) values(0);
Query OK, 1 row affected (0.01 sec)
    ## 没报错,因为在范围内,插入到表中的也是0
 
mysql> insert into test11(id) values(255);
Query OK, 1 row affected (0.01 sec)
    ## 没报错,因为在范围内,插入到表中的也是255
 
mysql> insert into test11(id) values(256);
Query OK, 1 row affected, 1 warning (0.00 sec)
　　 ## 不在范围内,插入没有报错(因为sql_mode中没有开启严格模式)
　　 ## 插入到表中的数据不是256,而是255
  
mysql> select * from test11;
+------+
| id   |
+------+
|    0 |
|    0 |
|  255 |
|  255 |
+------+
4 rows in set (0.00 sec)

## 设置会话模式下的sql_mode中包含strict_trans_tables
mysql> set session sql_mode="STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
Query OK, 0 rows affected (0.00 sec)
 
mysql> select @@sql_mode\G
*************************** 1. row ***************************
@@sql_mode: STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
1 row in set (0.00 sec)
 
## 创建test2测试表（这里指定了zerofill,会前导零填充,同时还会带上unsigned）
mysql> CREATE TABLE IF NOT EXISTS test2(
    -> id tinyint zerofill
    -> )engine=innodb character set utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.01 sec)
     ## id字段类型是tinyint zerofill,范围就是0~255,其长度是3;因为255的长度是3;

 ## 查看test2表的表结构
mysql> desc test2;
+-------+------------------------------+------+-----+---------+-------+
| Field | Type                         | Null | Key | Default | Extra |
+-------+------------------------------+------+-----+---------+-------+
| id    | tinyint(3) unsigned zerofill | YES  |     | NULL    |       |
+-------+------------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)
 
## 测试插入范围0~255范围整数和不在该范围内的整数
mysql> insert into test2 values(-1);   # 插入数值-1,错误(不在0~255范围内)
ERROR 1264 (22003): Out of range value for column 'id' at row 1
 
mysql> insert into test2 values(0);    # 插入数值0,正常(在0~255范围内)
Query OK, 1 row affected (0.06 sec)
 
mysql> insert into test2 values(255);  # 插入数值255,正常(在0~255范围内)
Query OK, 1 row affected (0.05 sec)
 
mysql> insert into test2 values(256);  # 插入数值256,错误(不在0~255范围内)
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)

## 设置会话模式下sql_mode中不包含strit_trans_tables变量
mysql> set session sql_mode="NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";

Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> select @@sql_mode\G
*************************** 1. row ***************************
@@sql_mode: NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
1 row in set (0.00 sec)

## 创建test22表（这里指定了zerofill,会前导零填充,同时还会带上unsigned）
mysql> create table if not exists test22(
    -> id tinyint zerofill
    -> )engine=innodb character set utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.00 sec)
 　## id字段类型是tinyint unsigned,范围就是0~255,其长度是3;因为255的长度是3;
 
## 查看test22表的表结构
mysql> desc test22;
+-------+------------------------------+------+-----+---------+-------+
| Field | Type                         | Null | Key | Default | Extra |
+-------+------------------------------+------+-----+---------+-------+
| id    | tinyint(3) unsigned zerofill | YES  |     | NULL    |       |
+-------+------------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)
 
## 测试插入范围0~255范围整数和不在该范围内的整数
mysql> insert into test22(id) values(-1);
Query OK, 1 row affected, 1 warning (0.00 sec)
　　## 不在范围,插入没报错(因为sql_mode中没有开启严格模式);
　　## 但到表中的不是-1,而是0,但因为有zerofill参数,所以显示时会前导零序填充;
 
mysql> insert into test22(id) values(0);
Query OK, 1 row affected (0.01 sec)
　　## 没报错,因为在范围内,插入到表中的也是0
 
mysql> insert into test22(id) values(255);
Query OK, 1 row affected (0.01 sec)
　　## 没报错,因为在范围内,插入到表中的也是255
 
mysql> insert into test22(id) values(256); 
Query OK, 1 row affected, 1 warning (0.00 sec)
　　## 不在范围,插入没报错（sql_mode中没有开启严格模式）
　　## 但到表中的数据不是256,而是255
 
mysql> select * from test22;
+------+
| id   |
+------+
|  000 |
|  000 |
|  255 |
|  255 |
+------+
4 rows in set (0.00 sec)

## 设置会话模式下的sql_mode中包含strict_trans_tables
mysql> set session sql_mode="STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
Query OK, 0 rows affected (0.00 sec)
 
mysql> select @@sql_mode\G
*************************** 1. row ***************************
@@sql_mode: STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
1 row in set (0.00 sec)
 
## 创建test3表（不加unsigned和zerofill）
mysql> CREATE TABLE test3(
    -> id tinyint
    -> )engine=innodb character set utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.06 sec)
 　　## id字段的类型为tinyint,其范围是-128至127,其显示长度是4,因为要显示符号("-")
 
## 查看test3表的表结构
mysql> desc test3;
+-------+------------+------+-----+---------+-------+
| Field | Type       | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| id    | tinyint(4) | YES  |     | NULL    |       |
+-------+------------+------+-----+---------+-------+
1 row in set (0.01 sec)
 
## 测试插入-128~127范围的整数和不在该范围内的整数
mysql> insert into test3(id) values(-129);  # 插入数值-129,错误,不在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1
 
mysql> insert into test3(id) values(-128);  # 插入数值-128,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test3(id) values(127);   # 插入数值127,正确,在范围内
Query OK, 1 row affected (0.01 sec)
 
mysql> insert into test3(id) values(128);   # 插入数值128,错误,不在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1
 
mysql> select * from test3;
+------+
| id   |
+------+
| -128 |
|  127 |
+------+
2 rows in set (0.00 sec)

## 设置会话模式下sql_mode中不包含strit_trans_tables变量
mysql> set session sql_mode="NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION";
Query OK, 0 rows affected, 1 warning (0.00 sec)
 
mysql> select @@sql_mode\G
*************************** 1. row ***************************
@@sql_mode: NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
1 row in set (0.00 sec)
 
## 创建test33表（不加unsigned和zerofill）
mysql> CREATE TABLE test33(
    -> id tinyint
    -> )engine=innodb character set utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.00 sec)
　　## id字段的类型为tinyint,其范围是-128至127,其显示长度是4,因为要显示符号("-")
 
## 查看test33表的表结构
mysql> desc test33;
+-------+------------+------+-----+---------+-------+
| Field | Type       | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| id    | tinyint(4) | YES  |     | NULL    |       |
+-------+------------+------+-----+---------+-------+
1 row in set (0.00 sec)
 

## 测试插入-128~127范围的整数和不在该范围内的整数
mysql> insert into test33(id) values(-129);
Query OK, 1 row affected, 1 warning (0.00 sec)
　　## 不在范围内,插入未报错,因为sql_mode中没有开启严格模式
　　## 插入到表中的不是-129,而是-128;
 
mysql> insert into test33(id) values(-128);
Query OK, 1 row affected (0.01 sec)
　　## 在范围内,插入不报错,插入的是多少就是多少
 
mysql> insert into test33(id) values(127);
Query OK, 1 row affected (0.00 sec)
　　## 在范围内,插入不报错,插入的是多少就是多少
 
mysql> insert into test33(id) values(128);
Query OK, 1 row affected, 1 warning (0.01 sec)
　　## 不在范围内,插入未报错,因为sql_mode中没有开启严格模式
　　## 插入到表中的不是128,而是127;
 
mysql> select * from test33;
+------+
| id   |
+------+
| -128 |
| -128 |
|  127 |
|  127 |
+------+
4 rows in set (0.00 sec)