Posted in MySQL onDecember 06, 2021
目录
1.1 tinyint类型说明
数据类型 | 显示长度 | 占用字节 | 有符号 | 无符号 |
---|---|---|---|---|
tinyint | 加上unsigned/zerofill:3 不加unsigned/zerofill:4 |
1(8bit) | -128至127 | 0至255 |
#### 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)。
1.2 实践环境说明
#### 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)
1.3 加unsigned属性
1.3.1 SQL模式开启严格模式
SQL_MODE中开启了严格模式,即SQL_MODE参数中包含STRICT_TRANS_TABLES参数
#### 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)
1.3.2 SQL模式未开启严格模式
SQL_MODE未开启严格模式,即SQL_MODE参数中不包含STRICT_TRANS_TABLES参数
#### 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)
1.4 加zerofill属性
1.4.1 SQL模式开启严格模式
SQL_MODE中开启了严格模式,即SQL_MODE参数中包含STRICT_TRANS_TABLES参数
## 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)
1.4.2 SQL模式未开启严格模式
SQL_MODE未开启严格模式,即SQL_MODE参数中不包含STRICT_TRANS_TABLES参数
## 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)
1.5 不加unsigned和zerofill属性
1.5.1 SQL模式开启严格模式
SQL_MODE中开启了严格模式,即SQL_MODE参数中包含STRICT_TRANS_TABLES参数
## 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)
1.5.2 SQL模式未开启严格模式
SQL_MODE中未开启严格模式,即SQL_MODE参数中不包含STRICT_TRANS_TABLES参数
## 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)
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mysql中整数数据类型tinyint详解
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