mysql 学习记录（三）--字段
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1.填充字段mysql> create database test1;Query OK, 1 row affected (0.02 sec)mysql> use test1;Database changedmysql> create table t1(id1 int,id2 int(5));Query OK, 0 rows affected (0.06 sec)mysql> insert into t1 values(1,1);Query OK, 1 row affected (0.02 sec)mysql> select * from t1;+------+------+| id1 | id2 |+------+------+| 1 | 1 |+------+------+1 row in set (0.00 sec)mysql> alter table t1 modify id1 int zerofill;Query OK, 1 row affected (0.05 sec)Records: 1 Duplicates: 0 Warnings: 0mysql> alter table t1 modify id2 int(5) zerofill;Query OK, 1 row affected (0.05 sec)Records: 1 Duplicates: 0 Warnings: 0mysql> select * from t1;+------------+-------+| id1 | id2 |+------------+-------+| 0000000001 | 00001 |+------------+-------+1 row in set (0.00 sec)mysql> insert into t1 values(1,1111111);Query OK, 1 row affected (0.01 sec)mysql> select * from t1;+------------+---------+| id1 | id2 |+------------+---------+| 0000000001 | 00001 || 0000000001 | 1111111 |+------------+---------+2 rows in set (0.00 sec)2.自增长字段的建立mysql> create table ai1(id int auto_increment not null primary key);Query OK, 0 rows affected (0.03 sec)mysql> create table ai2(id int auto_increment not null,primary key(id));Query OK, 0 rows affected (0.03 sec)mysql> create table ai3(id int auto_increment not null,unique(id));Query OK, 0 rows affected (0.03 sec)3.带小数的字段设置mysql> alter table t1 rename t1_test;Query OK, 0 rows affected (0.02 sec)mysql> desc t1_test;+-------+---------------------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+---------------------------+------+-----+---------+-------+| id1 | int(10) unsigned zerofill | YES | | NULL | || id2 | int(5) unsigned zerofill | YES | | NULL | |+-------+---------------------------+------+-----+---------+-------+2 rows in set (0.00 sec)mysql> create table t1( id1 float(5,2) default null, id2 double(5,2) default null, id3 decimal(5,2) default null);Query OK, 0 rows affected (0.03 sec)mysql> insert into t1 values(1.23,1.23,1.23);Query OK, 1 row affected (0.01 sec)mysql> select * from t1;+------+------+------+| id1 | id2 | id3 |+------+------+------+| 1.23 | 1.23 | 1.23 |+------+------+------+1 row in set (0.00 sec)mysql> insert into t1 values(1.234,1.234,1.23);Query OK, 1 row affected (0.02 sec)mysql> select * from t1;+------+------+------+| id1 | id2 | id3 |+------+------+------+| 1.23 | 1.23 | 1.23 || 1.23 | 1.23 | 1.23 |+------+------+------+2 rows in set (0.00 sec)mysql> insert into t1 values(1.234,1.234,1.234);Query OK, 1 row affected, 1 warning (0.01 sec)mysql> select * from t1;+------+------+------+| id1 | id2 | id3 |+------+------+------+| 1.23 | 1.23 | 1.23 || 1.23 | 1.23 | 1.23 || 1.23 | 1.23 | 1.23 |+------+------+------+3 rows in set (0.00 sec)mysql> show warnings;mysql> select * from t1;+------+------+------+| id1 | id2 | id3 |+------+------+------+| 1.23 | 1.23 | 1.23 || 1.23 | 1.23 | 1.23 || 1.23 | 1.23 | 1.23 |+------+------+------+3 rows in set (0.00 sec)mysql> alter table t1 modify id1 float;Query OK, 0 rows affected (0.02 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> alter table t1 modify id2 double;Query OK, 0 rows affected (0.01 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> alter table t1 modify id3 decimal;Query OK, 3 rows affected, 3 warnings (0.04 sec)Records: 3 Duplicates: 0 Warnings: 3mysql> insert into t1 values(1.234,1.234,1.234);Query OK, 1 row affected, 1 warning (0.01 sec)mysql> show warnings;+-------+------+------------------------------------------+| Level | Code | Message |+-------+------+------------------------------------------+| Note | 1265 | Data truncated for column 'id3' at row 1 |+-------+------+------------------------------------------+1 row in set (0.00 sec)mysql> select * from t1;+-------+-------+------+| id1 | id2 | id3 |+-------+-------+------+| 1.23 | 1.23 | 1 || 1.23 | 1.23 | 1 || 1.23 | 1.23 | 1 || 1.234 | 1.234 | 1 |+-------+-------+------+4 rows in set (0.00 sec)mysql> create table t2(id bit(1));Query OK, 0 rows affected (0.02 sec)mysql> desc t2;+-------+--------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+--------+------+-----+---------+-------+| id | bit(1) | YES | | NULL | |+-------+--------+------+-----+---------+-------+1 row in set (0.00 sec)mysql> insert into t2 values(1);Query OK, 1 row affected (0.01 sec)mysql> select bin(id),hex(id) from t2;+---------+---------+| bin(id) | hex(id) |+---------+---------+| 1 | 1 |+---------+---------+1 row in set (0.00 sec)mysql> insert into t2 values(2);Query OK, 1 row affected, 1 warning (0.00 sec)mysql> show warnings;+---------+------+---------------------------------------------+| Level | Code | Message |+---------+------+---------------------------------------------+| Warning | 1264 | Out of range value for column 'id' at row 1 |+---------+------+---------------------------------------------+1 row in set (0.00 sec)mysql> alter table t2 modify id bit(2);Query OK, 2 rows affected (0.04 sec)Records: 2 Duplicates: 0 Warnings: 0mysql> insert into t2 values(2);Query OK, 1 row affected (0.01 sec)mysql> select bin(id),hex(id) from t2;+---------+---------+| bin(id) | hex(id) |+---------+---------+| 1 | 1 || 1 | 1 || 10 | 2 |+---------+---------+3 rows in set (0.00 sec)mysql> create table t(d date,t time ,dt datetime);Query OK, 0 rows affected (0.02 sec)mysql> desc t;+-------+----------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+----------+------+-----+---------+-------+| d | date | YES | | NULL | || t | time | YES | | NULL | || dt | datetime | YES | | NULL | |+-------+----------+------+-----+---------+-------+3 rows in set (0.00 sec)4.与时间有关的字段设置mysql> insert into t values(now(),now(),now());Query OK, 1 row affected, 1 warning (0.01 sec)mysql> select * from t;+------------+----------+---------------------+| d | t | dt |+------------+----------+---------------------+| 2015-10-02 | 06:04:42 | 2015-10-02 06:04:42 |+------------+----------+---------------------+1 row in set (0.00 sec)mysql> alter table t rename t_test;Query OK, 0 rows affected (0.01 sec)mysql> create table t(id1 timestamp);Query OK, 0 rows affected (0.02 sec)mysql> desc t;+-------+-----------+------+-----+-------------------+-----------------------------+| Field | Type | Null | Key | Default | Extra |+-------+-----------+------+-----+-------------------+-----------------------------+| id1 | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |+-------+-----------+------+-----+-------------------+-----------------------------+1 row in set (0.00 sec)mysql> insert into t values(null);Query OK, 1 row affected (0.01 sec)mysql> select * from t;+---------------------+| id1 |+---------------------+| 2015-10-02 06:05:20 |+---------------------+1 row in set (0.00 sec)mysql> alter table t add id2 timestamp;Query OK, 1 row affected (0.04 sec)Records: 1 Duplicates: 0 Warnings: 0mysql> show create table t \G;*************************** 1. row *************************** Table: tCreate Table: CREATE TABLE `t` ( `id1` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, `id2` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00') ENGINE=InnoDB DEFAULT CHARSET=utf81 row in set (0.00 sec)ERROR: No query specifiedmysql> create table t8( id1 timestamp not null default current_timestamp, id2 datetime default null );Query OK, 0 rows affected (0.03 sec)mysql> show variables like 'time_zone';+---------------+--------+| Variable_name | Value |+---------------+--------+| time_zone | SYSTEM |+---------------+--------+1 row in set (0.00 sec)mysql> select * from t8 ;Empty set (0.00 sec)mysql> insert into t8 values(now(),now());Query OK, 1 row affected (0.00 sec)mysql> select * from t8;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 06:07:16 | 2015-10-02 06:07:16 |+---------------------+---------------------+1 row in set (0.00 sec)mysql> set time_zone='+9:00';Query OK, 0 rows affected (0.00 sec)mysql> select * from t8;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:07:16 | 2015-10-02 06:07:16 |+---------------------+---------------------+1 row in set (0.00 sec)mysql> desc t8;+-------+-----------+------+-----+-------------------+-------+| Field | Type | Null | Key | Default | Extra |+-------+-----------+------+-----+-------------------+-------+| id1 | timestamp | NO | | CURRENT_TIMESTAMP | || id2 | datetime | YES | | NULL | |+-------+-----------+------+-----+-------------------+-------+2 rows in set (0.00 sec)mysql> desc t;+-------+-----------+------+-----+---------------------+-----------------------------+| Field | Type | Null | Key | Default | Extra |+-------+-----------+------+-----+---------------------+-----------------------------+| id1 | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP || id2 | timestamp | NO | | 0000-00-00 00:00:00 | |+-------+-----------+------+-----+---------------------+-----------------------------+2 rows in set (0.00 sec)mysql> insert into t(id1) values('19700101080001');Query OK, 1 row affected, 1 warning (0.01 sec)mysql> select * from t;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:05:20 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 |+---------------------+---------------------+2 rows in set (0.00 sec)mysql> insert into t(id1) values(19700101080001);Query OK, 1 row affected, 1 warning (0.01 sec)mysql> select * from t;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:05:20 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 |+---------------------+---------------------+3 rows in set (0.00 sec)mysql> insert into t(id1) values(19700101080000);Query OK, 1 row affected, 1 warning (0.01 sec)mysql> select * from t;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:05:20 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 |+---------------------+---------------------+4 rows in set (0.00 sec)mysql> show warnings;Empty set (0.00 sec)mysql> desc t1;+-------+---------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+---------------+------+-----+---------+-------+| id1 | float | YES | | NULL | || id2 | double | YES | | NULL | || id3 | decimal(10,0) | YES | | NULL | |+-------+---------------+------+-----+---------+-------+3 rows in set (0.01 sec)mysql> desc t;+-------+-----------+------+-----+---------------------+-----------------------------+| Field | Type | Null | Key | Default | Extra |+-------+-----------+------+-----+---------------------+-----------------------------+| id1 | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP || id2 | timestamp | NO | | 0000-00-00 00:00:00 | |+-------+-----------+------+-----+---------------------+-----------------------------+2 rows in set (0.00 sec)mysql> insert into t(id1) value('2038-01-19 11:14:07');Query OK, 1 row affected (0.01 sec)mysql> select * from t;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:05:20 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 2038-01-19 11:14:07 | 0000-00-00 00:00:00 |+---------------------+---------------------+5 rows in set (0.00 sec)mysql> insert into t(id1) value('2038-01-19 11:14:08');Query OK, 1 row affected (0.02 sec)mysql> select * from t;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:05:20 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 2038-01-19 11:14:07 | 0000-00-00 00:00:00 || 2038-01-19 11:14:08 | 0000-00-00 00:00:00 |+---------------------+---------------------+6 rows in set (0.00 sec)mysql> insert into t(id1) value('2097-01-19 11:14:08');Query OK, 1 row affected, 1 warning (0.01 sec)mysql> select * from t;+---------------------+---------------------+| id1 | id2 |+---------------------+---------------------+| 2015-10-02 22:05:20 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 || 2038-01-19 11:14:07 | 0000-00-00 00:00:00 || 2038-01-19 11:14:08 | 0000-00-00 00:00:00 || 0000-00-00 00:00:00 | 0000-00-00 00:00:00 |+---------------------+---------------------+7 rows in set (0.00 sec)mysql> alter table t rename t_date;Query OK, 0 rows affected (0.02 sec)mysql> create table t(y year);Query OK, 0 rows affected (0.02 sec)mysql> desc t;+-------+---------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+---------+------+-----+---------+-------+| y | year(4) | YES | | NULL | |+-------+---------+------+-----+---------+-------+1 row in set (0.00 sec)mysql> insert into t values(2100);Query OK, 1 row affected (0.02 sec)mysql> select * from t;+------+| y |+------+| 2100 |+------+1 row in set (0.00 sec)mysql> create table t6(dt datetime);Query OK, 0 rows affected (0.02 sec)mysql> insert into t6 values('2007-9-3 12:10:10');Query OK, 1 row affected (0.00 sec)mysql> insert into t6 values('2007/9/3 12+10+10');Query OK, 1 row affected (0.00 sec)mysql> insert into t6 values('20070903121010');Query OK, 1 row affected (0.00 sec)mysql> insert into t6 values(20070903121010);Query OK, 1 row affected (0.01 sec)mysql> select * from t6;+---------------------+| dt |+---------------------+| 2007-09-03 12:10:10 || 2007-09-03 12:10:10 || 2007-09-03 12:10:10 || 2007-09-03 12:10:10 |+---------------------+4 rows in set (0.01 sec)5.varchar与char字段的长度mysql> create table vc(v varchar(4),c char(4));Query OK, 0 rows affected (0.02 sec)mysql> insert into vc values('ab ','ab ');Query OK, 1 row affected (0.01 sec)mysql> select length(v),length(c) from vc;+-----------+-----------+| length(v) | length(c) |+-----------+-----------+| 3 | 2 |+-----------+-----------+1 row in set (0.00 sec)mysql> select concat(v,'+'),concat(c,'+') from vc;+---------------+---------------+| concat(v,'+') | concat(c,'+') |+---------------+---------------+| ab + | ab+ |+---------------+---------------+1 row in set (0.00 sec)mysql> drop table t;Query OK, 0 rows affected (0.02 sec)mysql> create table t (c binary(3));Query OK, 0 rows affected (0.02 sec)mysql> insert into t set c='a';Query OK, 1 row affected (0.01 sec)mysql> select *,hex(c),c='a',c='a\0',c='a\0\0' from t;+------+--------+-------+---------+-----------+| c | hex(c) | c='a' | c='a\0' | c='a\0\0' |+------+--------+-------+---------+-----------+| a | 610000 | 0 | 0 | 1 |+------+--------+-------+---------+-----------+1 row in set (0.00 sec)mysql> alter table t rename t_binary;Query OK, 0 rows affected (0.02 sec)6.枚举型字段mysql> create table t(gender enum('M','F'));Query OK, 0 rows affected (0.02 sec)mysql> insert into t values('m'),('1'),('f'),(null);Query OK, 4 rows affected (0.01 sec)Records: 4 Duplicates: 0 Warnings: 0mysql> select * from t;+--------+| gender |+--------+| M || M || F || NULL |+--------+4 rows in set (0.01 sec)mysql> alter table t rename t_enum;Query OK, 0 rows affected (0.01 sec)7.set类型字段设置mysql> create table t(col set ('a','b','c','d' ));Query OK, 0 rows affected (0.03 sec)mysql> insert into t value('a,b'),('a,d,a'),('a,b'),('a,c'),('a');Query OK, 5 rows affected (0.01 sec)Records: 5 Duplicates: 0 Warnings: 0mysql> select * from t;+------+| col |+------+| a,b || a,d || a,b || a,c || a |+------+5 rows in set (0.00 sec) 0 0
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