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mysql 安裝 和簡(jiǎn)單使用技巧1

發(fā)布時(shí)間:2020-07-20 21:20:13 來源:網(wǎng)絡(luò) 閱讀:271 作者:冰山劍客 欄目:數(shù)據(jù)庫


# mysql_install_db  --user=mysql -datadir=/var/lib/mysql   初始化數(shù)據(jù)



vncviewer  172.40.50.117:6000


內(nèi)存 cpu 硬盤


# yum grouplist





                                  mysql(3306)


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1.用rpm裝 使用光盤封裝好的rpm包


[root@host ~]# yum -y install mysql-server

..........................

[root@host ~]# rpm -q mysql-server  (查看是否安裝和版本號(hào))

mysql-server-5.1.73-5.el6_6.x86_64

[root@host ~]# yum list |grep mysql-server 

mysql-server.x86_64                    5.1.73-5.el6_6                    @abc  

[root@host ~]# service  mysqld start  

初始化 MySQL 數(shù)據(jù)庫: WARNING: The host 'host.tedu.cn' could not be looked up with resolveip.


[root@host ~]# service mysqld status

mysqld (pid  21119) 正在運(yùn)行...

[root@host ~]# chkconfig mysqld on

[root@host ~]# chkconfig --list  mysqld 

mysqld         0:關(guān)閉 1:關(guān)閉 2:啟用 3:啟用 4:啟用 5:啟用 6:關(guān)閉


[root@host ~]# grep mysql /etc/passwd 

mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash




/var/lib/mysql   (數(shù)據(jù)庫目錄) 下面目錄和文件用戶和組都是mysql


/etc/my.cnf   主配置文件


/var/log/mysqld.log (日志文件)


/var/run/mysqld/mysqld.conf  (pid路徑)


[root@proxe ~]# which mysql

/usr/bin/mysql

[root@proxe ~]# rpm -qf /usr/bin/mysql

mysql-5.1.73-5.el6_6.x86_64



低版本:


進(jìn)程名和服務(wù)名都是mysqld


傳輸協(xié)議tcp


rmp包裝 進(jìn)程所有者和所屬組是mysql這個(gè)用戶




——--------------------------------------------------------------------

低版本:


(自己連:)mysql -hlocalhost  -uroot -p (本機(jī)登也可 mysql)


(別人練:)# mysql -h  ip

-------------------------------------------------------------------------


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2.從官網(wǎng)上下載安裝 (先把之前rpm裝的刪除)


1)刪除之前安裝的

[root@host ~]# service mysqld stop

停止 mysqld:                                              [確定]


[root@host ~]# rpm -e --nodeps mysql-server mysql     (--nodeps忽略依賴關(guān)系 就是依賴關(guān)系包不卸載   mysql連接工具卸載掉 因?yàn)橄旅嫜b的會(huì)有)


[root@host ~]# rm -fr  /etc/my.cnf 

[root@host ~]# rm -fr /var/lib/mysql/*


2)把官網(wǎng)下的解包安裝

[root@host ~]# tar -xvf MySQL-5.6.rpm.tar


MySQL-shared-5.6.15-1.el6.x86_64.rpm

MySQL-devel-5.6.15-1.el6.x86_64.rpm

MySQL-embedded-5.6.15-1.el6.x86_64.rpm

MySQL-test-5.6.15-1.el6.x86_64.rpm

MySQL-server-5.6.15-1.el6.x86_64.rpm

MySQL-shared-compat-5.6.15-1.el6.x86_64.rpm

MySQL-client-5.6.15-1.el6.x86_64.rpm


[root@host ~]# rpm -Uvh MySQL-*.rpm    (因?yàn)樯厦嬷粍h除了主配置文件,和mysql-server這個(gè)包 所有的依賴包還在 所以大U直接升級(jí))



[root@host ~]# rpm -qa |grep -i mysql

MySQL-test-5.6.15-1.el6.x86_64

MySQL-server-5.6.15-1.el6.x86_64

MySQL-client-5.6.15-1.el6.x86_64

MySQL-embedded-5.6.15-1.el6.x86_64

MySQL-shared-5.6.15-1.el6.x86_64

perl-DBD-MySQL-4.013-3.el6.x86_64

MySQL-devel-5.6.15-1.el6.x86_64

MySQL-shared-compat-5.6.15-1.el6.x86_64


[root@host ~]# service mysql start

Starting MySQL.. SUCCESS! 

[root@host ~]# netstat -anptu |grep :3306

tcp        0      0 :::3306                     :::*                        LISTEN      21509/mysqld  


[root@host t]# which mysql

/usr/bin/mysql

[root@host t]# rpm -qf /usr/bin/mysql

MySQL-client-5.6.15-1.el6.x86_64

[root@host t]# rpm -q MySQL-client    (高版本mysql包名叫這)

MySQL-client-5.6.15-1.el6.x86_64






3)高版本使用:會(huì)有密碼,在/root/.mysql_secret下 進(jìn)去需要該密碼才能使用。


[root@host ~]# cat /root/.mysql_secret 

# The random password set for the root user at Wed Feb 22 07:54:48 2017 (local time): 1eFb6CeJ


[root@host ~]# mysql -hlocalhost -uroot -p1eFb6CeJ




mysql> set password   for  root@"localhost"=password("123");

Query OK, 0 rows affected (0.03 sec)






____________________________________________________________________________________________________

[root@proxe mysql]# ls

auto.cnf     ib_logfile1  performance_schema  RPM_UPGRADE_HISTORY

ibdata1      mysql        proxe.tedu.cn.err   RPM_UPGRADE_MARKER-LAST

ib_logfile0  mysql.sock   proxe.tedu.cn.pid   test

[root@proxe mysql]# mysql -hlocalhost -uroot -pHYwSHnwN

Warning: Using a password on the command line interface can be insecure.

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)


[root@proxe mysql]# ln -s /var/lib/mysql/mysql.sock  /tmp/mysql.sock  或創(chuàng)建一個(gè)這樣的文件在這

________________________________________________________________________________________________________











高版本:

服務(wù)名mysql 

進(jìn)程名mysqld(

http傳輸協(xié)議:tcp


rpm包裝的,進(jìn)程所有者和所有組都是mysql


數(shù)據(jù)庫目錄:/var/lib/mysql


主配置文件:/etc/my.cnf





/var/run/mysqld/mysqld.conf    主配置文件


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

數(shù)據(jù)遷移 


mysql ---->mariadb



關(guān)系型數(shù)據(jù)庫mysql  難度大

非關(guān)系型數(shù)據(jù)庫            redis  簡(jiǎn)單 用戶名密碼





使用數(shù)據(jù)庫服務(wù)

啟動(dòng)

停止

狀態(tài)

連接




DDL 就是刪表刪庫建表建庫





以文件的形式存放在數(shù)據(jù)庫目錄下  /var/lib/mydql






DB   (/var/lib/mysql)

DBS  (裝列數(shù)據(jù)庫和操作系統(tǒng))

DBMS  (mysql)


E-R數(shù)據(jù)模型




字符類型:char  varchar  blob  text 

數(shù)值類型:int  tinyint  smallint

日期時(shí)間類型:year date  time  datetime

枚舉類型 enmu(單選項(xiàng))

        set(多個(gè))



字符:

char        255   定長(zhǎng)  不指默認(rèn)是(1)

varchar     65532     變長(zhǎng)  一定要指

大文本類型  blob  /  text  不要指


數(shù)值:

整型       微小×××(-128—127  0-255)tinyint默認(rèn)有符號(hào)     tinyint unsigned(無符號(hào))


         小×××         中整型       大×××       極大整型  

浮點(diǎn)型 float(單精度)  double(雙)


正整數(shù) 12

負(fù)整數(shù)-12


int(2)顯示寬度   默認(rèn)11位, 沒到這么多位會(huì)補(bǔ)。     zerofill,





日期時(shí)間:

  year 年   YYYY  2017      --2155

date  日期  YYYYMMDD  20170223

time  時(shí)間  HHMMSS   165425

  datetime / timestamp  

   YYYYMMDDHHMMSS   

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++





++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



基本操做:

[root@host ~]# mysql -uroot -p123


mysql> show databases;

mysql> use yy;


mysql> select database();


mysql> create database y;


mysql> create table t1(

    -> name char(4)

    -> );

mysql> desc t1;


mysql> insert into t1 

    -> values

    -> ("tom"

    -> );


mysql> select * from t1;

mysql> delete from t1;

mysql> drop table t1;

mysql> drop database y;

______________________________________________________________________________________________


對(duì)表的操作:

————————————————————————————————————————

字符類型 (姓名  家庭地址) 

char      定長(zhǎng)  <=255     默認(rèn)不指是1

varchar   變長(zhǎng)   <=65532  不指報(bào)錯(cuò)

               

大文本類型

blob

text


-----------------------


mysql> create table t2 (name char, home varchar(5) );

Query OK, 0 rows affected (0.67 sec)

mysql> desc t2;

+-------+------------+------+-----+---------+-------+

| Field | Type       | Null | Key | Default | Extra |

+-------+------------+------+-----+---------+-------+

| name  | char(1)    | YES  |     | NULL    |       |

| home  | varchar(5) | YES  |     | NULL    |       |

+-------+------------+------+-----+---------+-------+

2 rows in set (0.00 sec)

mysql> insert into t2 

    -> values

    -> ("tom","zhangh");

ERROR 1406 (22001): Data too long for column 'name' at row 1

mysql> insert into t2  values ("t","zhangh");

ERROR 1406 (22001): Data too long for column 'home' at row 1

mysql> insert into t2  values ("t","zhang");

Query OK, 1 row affected (0.11 sec)


mysql> select * from t2;

+------+-------+

| name | home  |

+------+-------+

| t    | zhang |

+------+-------+


字符類型:char 最長(zhǎng)不超過255個(gè)字符,默認(rèn)不指是1,輸值時(shí)不能對(duì)于指定字符但可以少于它。

  varshar 最長(zhǎng)不超65532個(gè)字符,默認(rèn)不指報(bào)錯(cuò),輸值時(shí)不能對(duì)于指定字符但可以少于它。

數(shù)據(jù)比較大時(shí),用blob,和text,   輸入字符數(shù)據(jù)時(shí)要用雙引引上。

————————————————————————————————————————————


整數(shù)類型 

————————


根據(jù)存儲(chǔ)數(shù)值的范圍又分為:  

       有符號(hào)         無符號(hào)

tinyint  微小整型    -128~127        0~255

smallint 

MEDIUMINT  

int    

bigint


        int(2)顯示寬度   默認(rèn)11位, 沒到這么多位會(huì)補(bǔ)。     int(2) zerofill,


tinyint 默認(rèn)是有符號(hào)數(shù)值為:-128--127 ,無符號(hào)數(shù)值為0--255 需要接unsigned(沒有負(fù)數(shù))   

     當(dāng)碰到小數(shù)都四舍五入。

      

mysql> create table t4(

    -> level tinyint);

Query OK, 0 rows affected (0.76 sec)


mysql> insert into t4  values (128);

mysql> insert into t4  values (127);

Query OK, 1 row affected (0.05 sec)

mysql> insert into t4  values (-170);

ERROR 1264 (22003): Out of range value for column 'level' at row 1

mysql> insert into t4  values (17.54);

Query OK, 1 row affected (0.05 sec)

mysql> insert into t4  values (17.44);

Query OK, 1 row affected (0.08 sec)

mysql> select * from t4;

+-------+

| level |

+-------+

|   127 |

|    18 |

|    17 |

+-------+

3 rows in set (0.00 sec)







mysql> create table t7( age int(3) zerofill);  int(也可默認(rèn)不寫)

mysql> insert into t8  value (1.5);

Query OK, 1 row affected (0.08 sec)


mysql> insert into t8  value (2.8);

Query OK, 1 row affected (0.08 sec)


mysql> insert into t8  value (3.2);

Query OK, 1 row affected (0.10 sec)

mysql> insert into t8  value (5452);

Query OK, 1 row affected (0.05 sec)


mysql> insert into t8  value (54);

Query OK, 1 row affected (0.03 sec)


mysql> select * from t8;

+------+

| age  |

+------+

|  002 |

|  003 |

|  003 |

| 5452 |

|  054 |


【int 后接zerofill 給定顯示寬度為3當(dāng)沒達(dá)到時(shí)會(huì)用0補(bǔ)齊】



float(n,m)浮點(diǎn)型


mysql> create table t9( age float(7,2));

Query OK, 0 rows affected (0.56 sec)


mysql> insert into t9 value(12345.1);

Query OK, 1 row affected (0.04 sec)


mysql> insert into t9 value(12345);

Query OK, 1 row affected (0.03 sec)


mysql> insert into t9 value(15);

Query OK, 1 row affected (0.03 sec)


mysql> insert into t9 value(15.215);

Query OK, 1 row affected (0.23 sec)


mysql> insert into t9 value(-15.215);

Query OK, 1 row affected (0.03 sec)


mysql> select * from t9;

+----------+

| age      |

+----------+

| 12345.10 |

| 12345.00 |

|    15.00 |

|    15.21 |

|   -15.21 |

+----------+


數(shù)值類型的寬度與字符類型寬度的區(qū)別?

數(shù)值類型的寬度是顯示寬度,不能夠控制給字段賦值的大小,字段值的大小由字段類型決定。




日期時(shí)間類型 (生日  注冊(cè)時(shí)間  入職時(shí)間)

年      year    YYYY        2016

                     01-69  20XX

                     70-99  19XX

                     00     0000


日期   date    YYYYMMDD  20161219

時(shí)間   time    HHMMSS    144518


日期時(shí)間   ( 約會(huì)時(shí)間 )

datetime / timestamp(當(dāng)給前面設(shè)置一個(gè)時(shí)間值是,它會(huì)自動(dòng)取當(dāng)前值)                     


YYYYMMDDHHMMSS 

20170214183018



datetime 與 timestamp   的區(qū)別?

當(dāng)不給timestamp類型的字段賦值時(shí),用系統(tǒng)當(dāng)前的時(shí)間給字段賦值。


create  table  t16(

time1  timestamp,

time2  datetime

);






++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++=

mysql> create table t17 ( time1  year, time2 date, time3 time, time5 datetime, time6 time );

Query OK, 0 rows affected (0.70 sec)

mysql> insert into t17 value (2017, 20160721, 141223, 20170721151515,  151615);

Query OK, 1 row affected (0.04 sec)


mysql> select * from t17;

+-------+------------+----------+---------------------+----------+

| time1 | time2      | time3    | time5 | time6               

+-------+------------+----------+---------------------+----------+

|  2017 | 2016-07-21 | 14:12:23 | 2017-07-21 15:15:15 | 15:16:15 |

+-------+------------+----------+---------------------+----------+

1 row in set (0.00 sec)



++++++++

mysql> create table t19 ( time1 timestamp, time2 datetime );


+-------+-----------+------+-----+-------------------+-----------------------------+

| Field | Type      | Null | Key | Default           | Extra                       |

+-------+-----------+------+-----+-------------------+-----------------------------+

| time1 | timestamp | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |

| time2 | datetime  | YES  |     | NULL              |                             |

+-------+-----------+------+-----+-------------------+-----------------------------+


mysql> insert into t19 values(20171219103003,20160521022223);

Query OK, 1 row affected (0.03 sec)


mysql> select * from t19;

+---------------------+---------------------+

| time1               | time2               |

+---------------------+---------------------+

| 2017-12-19 10:30:03 | 2016-05-21 02:22:23 |

+---------------------+---------------------+

1 row in set (0.00 sec)

+++++++

mysql> insert into t19(time1) value(20190512131452);

Query OK, 1 row affected (0.11 sec)


mysql> select * from t19;

+---------------------+---------------------+

| time1               | time2               |

+---------------------+---------------------+

| 2017-12-19 10:30:03 | 2016-05-21 02:22:23 |

| 2019-05-12 13:14:52 | NULL                |

+---------------------+---------


++++

mysql> create table t20( name char(10), age  int, tim1 time, tim2 date);

mysql> insert into t20(name,tim1) value("tom",151516);

mysql> select * from t20;

+------+------+----------+------+

| name | age  | tim1     | tim2 |

+------+------+----------+------+

| tom  | NULL | 15:15:16 | NULL |

+------+------+----------+------+

1 row in set (0.00 sec)



+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



使用時(shí)間函數(shù)獲取時(shí)間給日期時(shí)間類型字段賦值?

now()  獲取當(dāng)前系統(tǒng)時(shí)間

year()  獲取年份

date() 獲取日期

month()   獲取月份

day()       獲取日期(幾號(hào))

time()  獲取時(shí)間

+++++++++++++++++++



select now();

select  year( now() );

select  month(now());

select   day (now());

aelect    date(now());

select  year( 20191224 );

select  date( now() );

+++++++++++++++++++++++++++++++++++++

mysql> select now();

+---------------------+

| now()               |

+---------------------+

| 2017-02-22 18:39:23 |

+---------------------+

1 row in set (0.00 sec)


mysql> select year(now());

+-------------+

| year(now()) |

+-------------+

|        2017 |

+-------------+

1 row in set (0.00 sec)


mysql> select year(20191224);

+----------------+

| year(20191224) |

+----------------+

|           2019 |

+----------------+

1 row in set (0.00 sec)


mysql> select date (now());

+--------------+

| date (now()) |

+--------------+

| 2017-02-22   |

+--------------+

1 row in set (0.00 sec)


mysql> select month(now());

+--------------+

| month(now()) |

+--------------+

|            2 |

+--------------+

1 row in set (0.00 sec)


mysql> select day(now());

+------------+

| day(now()) |

+------------+

|         22 |

+------------+

1 row in set (0.00 sec)

mysql> select date(now());

+-------------+

| date(now()) |

+-------------+

| 2017-02-22  |

+-------------+

1 row in set (0.00 sec)


+++++++++++++++++++++++++++++++++++++++

insert into  t15  values("lili",21,18800.88,093000,20171008,1995,now());

insert into  t15  values("jerry",29,28800.88,now(),now(),now(),now());

insert into  t15  values("tom",21,18800.88,time(20171224201818),date(20171224201818),year(now()),now());





枚舉類型  (愛好    性別   專業(yè) )

字段的值只能在列舉的范圍內(nèi)選擇

enum(值列表)  單選

set(值列表)   多選


create   table  t177(

name  char(10),

sex   enum(0,1),

likes  set("book","game","film","music")

);


create   table  t17(

name  char(10),

sex   enum("boy","girl","no"),

likes  set("book","game","film","music")

);


desc  t17;

insert  into  t17  values("bob","boy","woman,game");

insert  into  t17  values("bob","boy","book,game");

insert  into  t17  values("alic",3,"game");

select  *  from  t17;




create  table  t5( name   text );

create  table  t5( name   blob );




++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

做一個(gè)學(xué)生表:

mysql> create table student( name char(10), age tinyint unsigned, level float(3,2), pay   float(7,2), sex   enum("man","woman"), likes set("book","music","film"), homeadder char(10), phone bigint,num  int(2) zerofill );


mysql> desc student

    -> ;

+-----------+----------------------------+------+-----+---------+-------+

| Field     | Type                       | Null | Key | Default | Extra |

+-----------+----------------------------+------+-----+---------+-------+

| name      | char(10)                   | YES  |     | NULL    |       |

| age       | tinyint(3) unsigned        | YES  |     | NULL    |       |

| level     | float(3,2)                 | YES  |     | NULL    |       |

| pay       | float(7,2)                 | YES  |     | NULL    |       |

| sex       | enum('man','woman')        | YES  |     | NULL    |       |

| likes     | set('book','music','film') | YES  |     | NULL    |       |

| homeadder | char(10)                   | YES  |     | NULL    |       |

| phone     | bigint(20)                 | YES  |     | NULL    |       |

| num       | int(2) unsigned zerofill   | YES  |     | NULL    |       |

+-----------+----------------------------+------+-----+---------+-------+

9 rows in set (0.00 sec)



mysql> insert into student value ("zhangsbing", 25, 1.711, 21203.222, 1, "book,music","shanghai", 18500202211, 2 );

mysql> mysql> select * from student;

+------------+------+-------+----------+------+------------+-----------+-------------+------+

| name       | age  | level | pay      | sex  | likes      | homeadder | phone       | num  |

+------------+------+-------+----------+------+------------+-----------+-------------+------+

| zhangsbing |   25 |  1.71 | 21203.22 | man  | book,music | shanghai  | 18500202211 |   02 |

+------------+------+-------+----------+------+------------+-----------+-------------+------+

1 row in set (0.00 sec)

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++




修改表結(jié)構(gòu)

alter   table   表名    執(zhí)行動(dòng)作;



mysql> desc student;

+-----------+----------------------------+------+-----+---------+-------+

| Field     | Type                       | Null | Key | Default | Extra |

+-----------+----------------------------+------+-----+---------+-------+

| name      | char(10)                   | YES  |     | NULL    |       |

| age       | tinyint(3) unsigned        | YES  |     | NULL    |       |

| level     | float(3,2)                 | YES  |     | NULL    |       |

| pay       | float(7,2)                 | YES  |     | NULL    |       |

| sex       | enum('man','woman')        | YES  |     | NULL    |       |

| likes     | set('book','music','film') | YES  |     | NULL    |       |

| homeadder | char(10)                   | YES  |     | NULL    |       |

| phone     | bigint(20)                 | YES  |     | NULL    |       |

| num       | int(2) unsigned zerofill   | YES  |     | NULL    |       |

+-----------+----------------------------+------+-----+---------+-------+

9 rows in set (0.00 sec)



________________

add 添加新字段

add  字段名   類型(寬度);

add  字段名   類型(寬度)  約束條件  ;

add  字段名   類型(寬度)  約束條件  first;

add  字段名   類型(寬度)  約束條件  after  字段名;



mysql> alter table student

    -> add

    -> class char(7) default "NSD1611" first,

    -> add

    -> class_uptime time  not null default 083000

    -> ;

mysql> mysql> select * from student;

+---------+------------+------+-------+----------+------+------------+-----------+-------------+------+--------------+

| class   | name       | age  | level | pay      | sex  | likes      | homeadder | phone       | num  | class_uptime |

+---------+------------+------+-------+----------+------+------------+-----------+-------------+------+--------------+

| NSD1611 | zhangsbing |   25 |  1.71 | 21203.22 | man  | book,music | shanghai  | 18500202211 |   02 | 08:30:00     |

+---------+------------+------+-------+----------+------+------------+-----------+-------------+------+--------------+

1 row in set (0.00 sec)


mysql> alter table student add university char(20) default "nongyedaxue" after class;

mysql> select * from student;

+---------+-------------+------------+------+-------+----------+------+------------+-----------+-------------+------+--------------+

| class   | university  | name       | age  | level | pay      | sex  | likes      | homeadder | phone       | num  | class_uptime |

+---------+-------------+------------+------+-------+----------+------+------------+-----------+-------------+------+--------------+

| NSD1611 | nongyedaxue | zhangsbing |   25 |  1.71 | 21203.22 | man  | book,music | shanghai  | 18500202211 |   02 | 08:30:00     |

+---------+-------------+------------+------+---

++++++++++++++++


drop  刪除字段

drop  字段名

alter table   t1  drop  name,drop  sex;


mysql> alter table student drop name,drop sex;


mysql> select * from student;

+---------+-------------+------+-------+----------+------------+-----------+-------------+------+--------------+

| class   | university  | age  | level | pay      | likes      | homeadder | phone       | num  | class_uptime |

+---------+-------------+------+-------+----------+------------+-----------+-------------+------+--------------+

| NSD1611 | nongyedaxue |   25 |  1.71 | 21203.22 | book,music | shanghai  | 18500202211 |   02 | 08:30:00     |

+---------+-------------+------+-------+----------+------------+-----------+-------------+------+--------------+


mysql> alter table student add sex enum("boy","girl") not null default "boy" after age;

mysql> mysql> select * from student;

+---------+-------------+------+-----+-------+----------+------------+-----------+-------------+------+--------------+

| class   | university  | age  | sex | level | pay      | likes      | homeadder | phone       | num  | class_uptime |

+---------+-------------+------+-----+-------+----------+------------+-----------+-------------+------+--------------+

| NSD1611 | nongyedaxue |   25 | boy |  1.71 | 21203.22 | book,music | shanghai  | 18500202211 |   02 | 08:30:00     |

+---------+-------------+------+-----+-------+----------+------------+-----------+-------------+------+--------------


mysql> alter table student

    -> modify

    -> sex enum("boy","girl","no") not null default "no";


mysql> mysql> select * from student;

+---------+-------------+------+-----+-------+----------+------------+-----------+-------------+------+--------------+

| class   | university  | age  | sex | level | pay      | likes      | homeadder | phone       | num  | class_uptime |

+---------+-------------+------+-----+-------+----------+------------+-----------+-------------+------+--------------+

| NSD1611 | nongyedaxue |   25 | boy |  1.71 | 21203.22 | book,music | shanghai  | 18500202211 |   02 | 08:30:00     |

+---------+-------------+------+-----+-------+----------+------------+-----------+-------------+------+--------------+

1 row in set (0.00 sec)


mysql> desc student;

+--------------+----------------------------+------+-----+-------------+-------+

| Field        | Type                       | Null | Key | Default     | Extra |

+--------------+----------------------------+------+-----+-------------+-------+

| class        | char(7)                    | YES  |     | NSD1611     |       |

| university   | char(20)                   | YES  |     | nongyedaxue |       |

| age          | tinyint(3) unsigned        | YES  |     | NULL        |       |

| sex          | enum('boy','girl','no')    | NO   |     | no          |       |

| level        | float(3,2)                 | YES  |     | NULL        |       |

| pay          | float(7,2)                 | YES  |     | NULL        |       |

| likes        | set('book','music','film') | YES  |     | NULL        |       |

| homeadder    | char(10)                   | YES  |     | NULL        |       |

| phone        | bigint(20)                 | YES  |     | NULL        |       |

| num          | int(2) unsigned zerofill   | YES  |     | NULL        |       |

| class_uptime | time                       | NO   |     | 08:30:00    |       |

+--------------+----------------------------+------+-----+-------------+-------+


















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