添加数据库[root@localhost ~]# mysql -uroot -p #进入mysql数据表`Enter password: Welcome to the MySQL monitor.
添加数据库
[root@localhost ~]# mysql -uroot -p #进入mysql数据表`Enter password: Welcome to the MySQL monitor. Commands end with ; or /g.Your MySQL connection id is 8...... #省略部分内容Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.mysql> show databases;+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys |+--------------------+4 rows in set (0.00 sec)mysql> create database school; #创建新库‘school
Query OK, 1 row affected (0.00 sec)
mysql> show databases; #查看所有库
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| school |
| sys |
+--------------------+
5 rows in set (0.00 sec)
添加数据表
mysql>use school;mysql> create table info (id int not null,name char(6),score decimal(5,2),age int(4))；Query OK, 0 rows affected (0.04 sec)mysql> desc info; #查看表结构+-------+--------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+--------------+------+-----+---------+-------+| id | int(11) | NO | | NULL | || name | char(6) | YES | | NULL | || score | decimal(5,2) | YES | NULL | || age | int(4) | YES | | NULL | |+-------+--------------+------+-----+---------+-------+添加数据表内容mysql> insert into info (id,name,score,age)values(1,'张三',88,33);Query OK, 1 row affected (0.01 sec)mysql> insert into info (id,name,score,age)values(2,'李四',48,31);Query OK, 1 row affected (0.01 sec)mysql> insert into info (id,name,score,age)values(3,'王五',68,27);Query OK, 1 row affected (0.00 sec)mysql> select * from info; #查看表内容+----+--------+-------+------+| id | name | score | age |+----+--------+-------+------+| 1 | 张三 | 88.00 | 33 || 2 | 李四 | 48.00 | 31 || 3 | 王五 | 68.00 | 27 |+----+--------+-------+------+添加表列mysql> alter table info add column score decimal(5,2);Query OK, 0 rows affected (0.05 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> select * from info; #查看表内容+----+--------+--------+-------+| id | name | hobbly | score |+----+--------+--------+-------+| 1 | zl | 看书 | NULL || 2 | 李四 | 上网 | NULL || 5 | kl | 游泳 | NULL |+----+--------+--------+-------+更改数据mysql> update info set score=82 where id=1; #更改id=1的学生成绩为82分Query OK, 1 row affected (0.01 sec)Rows matched: 1 Changed: 1 Warnings: 0mysql> select * from info; #查看更改效果+----+--------+-------+------+| id | name | score | age |+----+--------+-------+------+| 1 | 张三 | 82.00 | 33 || 2 | 李四 | 48.00 | 31 || 3 | 王五 | 68.00 | 27 |+----+--------+-------+------+删除数据表mysql> drop table info;Query OK, 0 rows affected (0.02 sec)mysql> show tables; #查看是否删除Empty set (0.00 sec) #已经删除（空表）删除库mysql> drop database school;Query OK, 0 rows affected (0.01 sec)mysql> show databases; #查看school数据库是否删除+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys |+--------------------+删除表列（记录条数）mysql> delete from info where hobbly=1;Query OK, 1 row affected (0.01 sec)mysql> select * from info;+----+--------+-------+------+--------+| id | name | score | age | hobbly |+----+--------+-------+------+--------+| 1 | 张三 | 82.00 | 33 | 3 || 2 | 李四 | 48.00 | 31 | 5 || 3 | 王五 | 68.00 | 27 | 4 || 2 | ff | 55 | 44 | 2 || 3 |ww | 33 |3 1 | 3 |+----+--------+-------+------+--------+删除表列（字段）mysql> select * from info; #查看数据表+----+--------+-------+--------+| id | name | score | hobbly |+----+--------+-------+--------+| 1 | zl | 88 | 看书 || 2 | 李四 | 68 | 上网 || 5 | kl | 88 | 游泳 |+----+--------+-------+--------+mysql> alter table info drop column score; #用alter删除表列mysql> select * from info; #再次查看数据表+----+--------+--------+| id | name | hobbly |+----+--------+--------+| 1 | zl | 看书 || 2 | 李四 | 上网 || 5 | kl | 游泳 |+----+--------+--------+