MySQL整数数据类型tinyint

一、tinyint类型说明

MySQL整数数据类型tinyint

id      tinyint(M)                          [UNSIGNED]  [ZEROFILL] 
字段名   字段类型(显示长度,生产中创建表时不指定)     [无符号]   [前导填充]

unsigned:
01:tinyint(M)后面加上unsigned后,就是无符号,只能插入正整数,范围就是0~255;
02:1字节就是8位,那么2的8次方-1就是255;
03:因为加了unsigned就是正整数,也就是无符号,所以范围是0~255;
04:255的长度是3,当不指定长度时,例如:tinyint unsigned其显示长度就是3,当插入
    的正整数长度不够3时,不会自动补充,也就是1显示1;255显示255;

zerofill:
01:加上zerofill,会把unsigned给带上,就是无符号,只能插入正整数,范围是0~255;
02:1字节就是8位,那么2的8次方-1就是255;
03:因为会带上unsigned参数,只能插入正整数,也就是无符号,所以范围是0~255;
04:255的长度是3,,不指定长度时,例如:tinyint zerofill其显示长度就是3,不管
   你插入的正整数长度达不到3时,用0前导填充;例:1显示001;255显示255;

不加unsigned和zerofill
不在tinyint后加上unsigned或zerofill,其默认是有符号,也就可插入正整数和负整数,且
最大的正整数和负整数的长度是3,但是因为要显示符号("-"),所以显示长度是4;虽然显示的
长度是4,但对于插入的数据的长度达不到4时,也不会自动前导零填充;

特别说明:
01:在为字段指定类型时,一般不指定数据类型的长度,例如:tinyint或tinyint unsigned
02:当插入数据若超出范围,能否插入成功,这个得根据sql_mode中是否开启严格模式,即   sql_mode参数中是否包含STRICT_TRANS_TABLES变量;

二、实践环境说明与准备

-- 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
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)

三、测试1【加unsigned参数】

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
    -> );
Query OK, 0 rows affected (0.06 sec)

  -- PS
  -- 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)

SQL_MODE中未开启严格模式,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 
    -> );
Query OK, 0 rows affected (0.00 sec)

  -- PS
  -- 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)

四、测试2【加zerofill参数】

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
    -> );
Query OK, 0 rows affected (0.01 sec)
	
  -- PS
  -- 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)

SQL_MODE中未开启严格模式,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
    -> );
Query OK, 0 rows affected (0.00 sec)

  -- PS
  -- 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)

五、测试3【不加zerofill和unsigned参数】

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
    -> );
Query OK, 0 rows affected (0.06 sec)

  -- PS
  -- 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)

SQL_MODE中未开启严格模式,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
    -> );
Query OK, 0 rows affected (0.00 sec)
  -- PS
  -- 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)

相关推荐