MySQL整数数据类型mediumint

烂漫一生 提交于 2020-02-18 07:52:35

一、mediumint类型说明

id       mediumint(M)                     [UNSIGNED]   [ZEROFILL] 
字段名  字段类型(显示长度,建表时不指定显示长度)   [无符号]     [前导填充]

unsigned:
01:mediumint (M)后面加上unsigned,就是无符号,只可插入正整数,范围就是0~16777215;
02:3字节就是24位,那么2的24次方减1就是16777215;
03:因为加了unsigned参数,也就是无符号,只可插入正整数,范围是0~16777215;
04:16777215长度是8;不指定mediumint长度,例如:smallint unsigned,其显示的长度就是
mediumint (8),但当插入的正整数的长度达不到长度8时,不会自动补充,也就1显示1;
16777215显示的就是16777215;

zerofill:
01:mediumint(M)后面加上zerofill参数,会把unsigned参数带上,也就是无符号,只可以插
入正整数,其范围是0~16777215;
02:3字节就是24位,那么2的24次方减1就是16777215;
03:因为会带上unsigned参数,所以就是正整数,也就是无符号,所以范围是0~16777215;
04:16777215的长度是8,不指定长度时,例如; mediumint zerofill,其显示长度就
是8,当你插入正整数长度达不到长度8时,会前导0填充,1显示00000001;16777215显
示16777215;

不加unsigned和zerofill
不在mediumint后加上unsigned或zerofill,其默认是有符号,也就可以插入正整数和负整
数,且正整数和负负整数的最大数的长度是8,但因为要显示符号("-"),长度是mediumint(9),
虽然显示的长度是9,但对于插入的整数的长度达不到长度9时,不会自动前导零填充;

特别说明
01:在创建表的时候,一般不指定其长度,例如:mediumin或mediumin unsigned
02:插入的数据若超出范围,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sql_mode中包含strict_trans_tables变量
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 mediumint unsigned
    -> );
Query OK, 0 rows affected (0.19 sec)

  -- PS
  -- 表test1的id字段加了unsigned参数,那么id字段的范围就是0~16777215;
  -- 显示显示应该是mediumint(8),因为16777215的长度是8;

-- 查看test1表的表结构
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type                  | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id    | mediumint(8) unsigned | YES  |     | NULL    |       |
+-------+-----------------------+------+-----+---------+-------+
1 row in set (0.10 sec)

-- 测试插入0~16777215范围内的整数和不在该范围内的整数
mysql> insert into test1(id) values(-1);       # 插入数值-1,错误,不在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> insert into test1(id) values(0);        # 插入数值0,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test1(id) values(16777215); # 插入数值16777215,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test1(id) values(16777216); # 插入数值16777216,错误,不在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> select * from test1;
+----------+
| id       |
+----------+
|        0 |
| 16777215 |
+----------+
2 rows in set (0.00 sec)

SQL_MODE末开启严格模式,即SQL_MODE参数中不包含STRICT_TRANS_TABLES参数

-- 设置会话模式下sql_mode中不开启严格模式,即不包含strict_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(这里加上unsigned,也就是无符号)
mysql> create table if not exists test11(
    -> id mediumint unsigned
    -> );
Query OK, 0 rows affected (0.01 sec)

  -- PS
  -- 表test1的id字段加了unsigned参数,那么id字段的范围就是0~16777215;
  -- 显示显示应该是mediumint(8),因为16777215的长度是8;

-- 查看test11表的表结构
mysql> desc test11;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type                  | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id    | mediumint(8) unsigned | YES  |     | NULL    |       |
+-------+-----------------------+------+-----+---------+-------+
1 row in set (0.00 sec)

-- 测试插入0~16777215范围内的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 (0.01 sec)
  -- 不在范围内,插入时未报错(因为sql_mode中未开启严格模式)
  -- 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 (0.00 sec)
   -- 在范围内,插入时不报错,插入的是什么就是什么

mysql> insert into test11(id) values(16777215);
Query OK, 1 row affected (0.01 sec)
   -- 在范围内,插入时不报错,插入的是什么就是什么

mysql> insert into test11(id) values(16777216);
Query OK, 1 row affected, 1 warning (0.00 sec)
  -- 不在范围内,插入时未报错(因为sql_mode中未开启严格模式)
  -- 插入到表中的数据不是16777216,而是16777215

mysql> select * from test11;
+----------+
| id       |
+----------+
|        0 |
|        0 |
| 16777215 |
| 16777215 |
+----------+
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sql_mode中包含strict_trans_tables变量
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表(这里指定了zerofill,也就是前导零填充)
mysql> create table if not exists test2(
    -> id mediumint zerofill
    -> );
Query OK, 0 rows affected (0.03 sec)

  -- PS
  -- id字段加了zerofile参数,它会把unsigned参数也带上,且会前导零填充;
  -- 范围就是0~16777215, 因为16777215的长度是8, 显示长度是mediumint(8);

-- 查看test2表的表结构
mysql> desc test2;
+-------+--------------------------------+------+-----+---------+-------+
| Field | Type                           | Null | Key | Default | Extra |
+-------+--------------------------------+------+-----+---------+-------+
| id    | mediumint(8) unsigned zerofill | YES  |     | NULL    |       |
+-------+--------------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)

-- 测试插入0~16777215范围内的整数和不在该范围内的整数
mysql> insert into test2(id) values(-1);       # 插入数值-1,错误,不在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> insert into test2(id) values(0);        # 插入数值0,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test2(id) values(16777215); # 插入数值16777215,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test2(id) values(16777216); # 插入数值16777216,错误,不在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> select * from test2;
+----------+
| id       |
+----------+
| 00000000 |
| 16777215 |
+----------+
2 rows in set (0.00 sec)

SQL_MODE末开启严格模式,即SQL_MODE参数中不包含STRICT_TRANS_TABLES参数

-- 设置会话模式下sql_mode中不开启严格模式,即不包含strict_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(加上zerofill参数,它会前导零填充,同时也会把unsigned带上)
mysql> create table if not exists test22(
    -> id mediumint zerofill
    -> );
Query OK, 0 rows affected (0.01 sec)

  -- PS
  -- id字段加了zerofile参数,它会把unsigned参数也带上,且会前导零填充;
  -- 范围就是0~16777215, 因为16777215的长度是8, 显示长度是mediumint(8);

-- 查看test22表的表结构
mysql> desc test22;
+-------+--------------------------------+------+-----+---------+-------+
| Field | Type                           | Null | Key | Default | Extra |
+-------+--------------------------------+------+-----+---------+-------+
| id    | mediumint(8) unsigned zerofill | YES  |     | NULL    |       |
+-------+--------------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)

-- 测试插入0~16777215范围内的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,插入未报错(因为sql_mode中未开启严格模式)
  -- 插入的数据不是-1,而是0,但显示时会前导零填充,因为加了zerofill参数

mysql> insert into test22(id) values(0);
Query OK, 1 row affected (0.00 sec)
  -- 在范围内,不报错,插入是多少就是多少,但显示时会前导零填充,因为加了zerofill参数

mysql> insert into test22(id) values(16777215);
Query OK, 1 row affected (0.00 sec)
  -- 在范围内,不报错,插入是多少就是多少

mysql> insert into test22(id) values(16777216);
Query OK, 1 row affected, 1 warning (0.00 sec)
  -- 不在范围,插入未报错(因为sql_mode中未开启严格模式)
  -- 插入的数据不是16777216,而是16777215

mysql> select * from test22;
+----------+
| id       |
+----------+
| 00000000 |
| 00000000 |
| 16777215 |
| 16777215 |
+----------+
4 rows in set (0.00 sec)

五、测试3【不加unsigned和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sql_mode中包含strict_trans_tables变量
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 if not exists test3(
    -> id mediumint
    -> );
Query OK, 0 rows affected (0.05 sec)

  -- PS
  -- 表test3的id字段没加unsigned和zerofile参数,那么id字段的范围就是-8388608~8388607
  -- 显示长度是9,因为-8388608和8388607的长度是8,但要显示符号("-"),所显示长度是9

-- 查看test3表的表结构
mysql> desc test3;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | mediumint(9) | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
1 row in set (0.00 sec)

-- 测试插入-8388608~8388607范围内的整数和不在该范围内的整数
mysql> insert into test3(id) values(-8388609);   # 插入数值-8388609,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(-8388608);   # 插入数值-8388608,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test3(id) values(8388607);    # 插入数值8388607,正确,在范围内
Query OK, 1 row affected (0.00 sec)

mysql> insert into test3(id) values(8388608);    # 插入数值8388608,错误,在范围内
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> select * from test3;
+----------+
| id       |
+----------+
| -8388608 |
|  8388607 |
+----------+
2 rows in set (0.00 sec)

SQL_MODE末开启严格模式,即SQL_MODE参数中不包含STRICT_TRANS_TABLES参数

-- 设置会话模式下sql_mode中不开启严格模式,即不包含strict_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参数)
mysql> create table if not exists test33(
    -> id mediumint
    -> );
Query OK, 0 rows affected (0.01 sec)

  -- PS
  -- 表test33的id字段没加unsigned和zerofile参数,那么id字段的范围就是-8388608~8388607
  -- 显示长度是9,因为-8388608和8388607的长度是8,但要显示符号("-"),所显示长度是9


-- 查看test33表的表结构
mysql> desc test33;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | mediumint(9) | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
1 row in set (0.00 sec)

-- 测试插入-8388608~8388607范围内的整数和不在该范围内的整数
mysql> insert into test33(id) values(-8388609);
Query OK, 1 row affected, 1 warning (0.00 sec)
  -- 不在范围内,插入未报错(因为sql_mode中未开启严格模式)
  -- 插入的数据不是-8388609,而是-8388608

mysql> insert into test33(id) values(-8388608);
Query OK, 1 row affected (0.00 sec)
    -- 在范围内,未报错,插入是多少就是多少

mysql> insert into test33(id) values(8388607);
Query OK, 1 row affected (0.00 sec)
  -- 在范围内,未报错,插入是多少就是多少

mysql> insert into test33(id) values(8388608);
Query OK, 1 row affected, 1 warning (0.00 sec)
  -- 不在范围内,插入未报错(因为sql_mode中未开启严格模式)
  -- 插入的数据不是8388608,而是8388607

mysql> select * from test33;
+----------+
| id       |
+----------+
| -8388608 |
| -8388608 |
|  8388607 |
|  8388607 |
+----------+
4 rows in set (0.00 sec)

  

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