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)
来源:https://www.cnblogs.com/chenliangc/p/11107300.html