mysql常用基本命令的使用

1.创建名为mycdb的数据库：

a.linux中直接从bash创建：

[root@test~]#mysqladmin -u root -p create mycdb

b.进入mysql数据库后

mysql> create database mycdb;

2.查看数据库：

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| jack               |
| mycdb              |
| mysql              |
| performance_schema |
| sakila             |
| sys                |
| world              |
+--------------------+
8 rows in set (0.00 sec)

3.删除mycdb这个数据库

a.linux中直接由bash中删除：

[root@test~]#mysqladmin -u root -p drop mycdb

b.进入mysql中删除：

mysql> drop database mycdb;
Query OK, 0 rows affected (0.00 sec)

4.选择mycdb这个数据库：

mysql> use mycdb;
Database changed

5.创建名为person的数据表

mysql> create table person(name VARCHAR(10),sex VARCHAR(1),age VARCHAR(10));

Query OK, 0 rows affected (1.55 sec)

6.查看数据库mycdb中的数据表:

mysql> show tables;
+-----------------+
| Tables_in_mycdb |
+-----------------+
| mycdb           |
| person          |
+-----------------+
2 rows in set (0.00 sec)

7.删除数据库mycdb中的数据表mycdb：

mysql> drop table mycdb;
Query OK, 0 rows affected (0.84 sec)

8.向person这个数据表中插入数据：

mysql> insert into person(name,sex,age) values('jay','m',35);
Query OK, 1 row affected (0.24 sec)

9.读取person数据表的内容：

mysql> select * from person;
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| jay     | m    | 35   |
| eason   | m    | 38   |
| naying  | f    | 42   |
| liuhuan | m    | 52   |
+---------+------+------+
4 rows in set (0.00 sec)

10.如何利用where：

mysql> select * from person where name='liuhuan';
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| liuhuan | m    | 52   |
+---------+------+------+
1 row in set (0.00 sec)

11.利用update修改person数据表中 name=‘eason’ 的数据age=43

mysql> update person set age=43 where name='eason';
Query OK, 1 row affected (0.27 sec)
Rows matched: 1  Changed: 1  Warnings: 0

12.利用delete删除person数据表中 name=‘wangfeng’ 的数据

mysql> delete from person where name='wangfeng';
Query OK, 1 row affected (0.24 sec)

13.mysql中的like语句，这个语句使用 % 表示任意字符，若没有 % 则如同 = 一样，可以用or或and连接一个或多个条件：

a.无 % 时候如 = ,选取person数据表中sex为‘m’的数据：

mysql> select * from person where sex like 'm';
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| jay     | m    | 35   |
| eason   | m    | 43   |
| liuhuan | m    | 52   |
+---------+------+------+
3 rows in set (0.00 sec)

 b.有 % 时匹配多个任意字符，选取person中name含有‘o’的数据：

mysql> select * from person where name like '%i%';
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| naying  | f    | 42   |
| liuhuan | m    | 52   |
+---------+------+------+
2 rows in set (0.00 sec)

14. mysql中union操作符；

union操作符用于对两个及以上的select句子进行连接并整合到一个结果中；

union有两个参数可选（all、distinct）；distinct（默认的）：多个select句子中有相同的数据会默认删除重复的数据再整合到一个结果；all：返回所有结果，包括重复的；

再创建一个名为sing的数据表

mysql> create table sing(name VARCHAR(15),sex VARCHAR(1),age VARCHAR(15));
mysql> show tables;
+-----------------+
| Tables_in_mycdb |
+-----------------+
| person          |
| sing            |
+-----------------+
mysql> desc sing;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name  | varchar(15) | YES  |     | NULL    |       |
| sex   | varchar(1)  | YES  |     | NULL    |       |
| age   | varchar(15) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+

mysql> insert into sing(name,sex,age) values('lx','m',12);
mysql> insert into sing(name,sex,age) values('gh','f',32);
mysql> insert into sing(name,sex,age) values('jkl','m',41);
mysql> insert into sing(name,sex,age) values('og','f',22);

mysql> insert into sing(name,sex,age) values('eason','m',43);

mysql> show tables;
+-----------------+
| Tables_in_mycdb |
+-----------------+
| person          |
| sing            |
+-----------------+

mysql> select * from sing;
+------+------+------+
| name | sex  | age  |
+------+------+------+
| lx   | m    | 12   |

| eason   | m    | 43   |
| gh   | f    | 32   |
| jkl  | m    | 41   |
| og   | f    | 22   |
+------+------+------+

mysql> select * from person;
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| jay     | m    | 35   |
| eason   | m    | 43   |
| naying  | f    | 42   |
| liuhuan | m    | 52   |
+---------+------+------+
4 rows in set (0.00 sec)


mysql> select * from person union select * from sing;
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| jay     | m    | 35   |
| eason   | m    | 43   |
| naying  | f    | 42   |
| liuhuan | m    | 52   |
| lx      | m    | 12   |

| gh      | f    | 32   |
| jkl     | m    | 41   |
| og      | f    | 22   |

+---------+------+------+
8 rows in set (0.00 sec)

a.默认筛选出person中sex=‘m’和sing中sex=‘m’的数据；

mysql> select * from person where sex='m' union select * from sing where sex='m';

+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| jay     | m    | 35   |
| eason   | m    | 43   |
| liuhuan | m    | 52   |
| lx      | m    | 12   |
| jkl     | m    | 41   |
+---------+------+------+
5 rows in set (0.00 sec)

b.使用union all来筛选：

mysql> select * from person where sex='m' union all select * from sing where sex='m';
+---------+------+------+
| name    | sex  | age  |
+---------+------+------+
| jay     | m    | 35   |
| eason   | m    | 43   |
| liuhuan | m    | 52   |
| lx      | m    | 12   |
| jkl     | m    | 41   |
| eason   | m    | 43   |
+---------+------+------+
6 rows in set (0.00 sec)