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MySQL管理数据库、数据表、数据的基本运作是什么

发布时间:2021-12-21 13:39:45 所属栏目:MySql教程 来源:互联网
导读:本篇内容主要讲解MySQL管理数据库、数据表、数据的基本操作是什么,感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷,实用性强。下面就让小编来带大家学习MySQL管理数据库、数据表、数据的基本操作是什么吧! 注意:MySQL数据库命令不区分大小写,但在Mac
本篇内容主要讲解“MySQL管理数据库、数据表、数据的基本操作是什么”,感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷,实用性强。下面就让小编来带大家学习“MySQL管理数据库、数据表、数据的基本操作是什么”吧!
 
注意:MySQL数据库命令不区分大小写,但在Mac端如果想使用tab键自动补全命令,就必须使用大写。
 
1、数据库管理
 
1.1 create 创建数据库
 
mysql> create database test;
Query OK, 1 row affected (0.50 sec)
1.2 show 查看所有数据库
 
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.32 sec)
1.3 alter 修改数据库
 
alter命令修改数据库编码:
 
一般我们设置的字符集使用的都是UTF8,若发现数据库编码不是UTF8,可使用该语句更改数据库编码:
 
mysql> alter database test character set utf8;
Query OK, 1 row affected (0.01 sec)
1.4 use 使用数据库
 
mysql> use test;
Database changed
1.5 查看当前使用的数据库
 
mysql> select database();
+------------+
| database() |
+------------+
| test |
+------------+
1 row in set (0.00 sec)
1.6 drop 删除数据库
 
mysql> drop database test;
Query OK, 0 rows affected (0.00 sec)
2、数据库表管理
 
我们先创建一个数据库,以供我们后面使用:
 
mysql> create database test;
Query OK, 1 row affected (0.06 sec)
创建后,使用use命令进入数据库:
 
mysql> use test;
Database changed
2.1 create 创建表
 
mysql> create table test(id int auto_increment primary key,
    -> name varchar(20) not null,
    -> age int not null,
    -> birthday datetime);
Query OK, 0 rows affected (0.14 sec)
2.2 show 显示表
 
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| test |
+----------------+
1 row in set (0.00 sec)
2.3 desc 查看表结构
 
mysql> desc test;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(20) | NO | | NULL | |
| age | int(11) | NO | | NULL | |
| birthday | datetime | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
4 rows in set (0.01 sec)
2.4 alter 修改表结构(增、删、改)
 
2.4.1 add 在表中添加字段(列)
 
mysql> alter table test add star bool;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
注意:在MySQL中布尔类型会自动转变为tinyint(1)类型
 
用desc查看可得到:
 
mysql> desc test;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(20) | NO | | NULL | |
| age | int(11) | NO | | NULL | |
| birthday | datetime | YES | | NULL | |
| star | tinyint(1) | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
2.4.2 modify 修改表字段(列)
 
mysql> alter table test modify star int;
Query OK, 0 rows affected (0.43 sec)
Records: 0 Duplicates: 0 Warnings: 0
注意:int可以指定长度,也可以不指定,不指定时默认长度为int(11),修改后再次用desc查看:
 
mysql> desc test;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(20) | NO | | NULL | |
| age | int(11) | NO | | NULL | |
| birthday | datetime | YES | | NULL | |
| star | int(11) | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
2.4.3 drop 删除表字段(列)
 
mysql> alter table test drop column star;
Query OK, 0 rows affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0
查看表结构可以看到没有star字段了:
 
mysql> desc test;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(20) | NO | | NULL | |
| age | int(11) | NO | | NULL | |
| birthday | datetime | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
2.4.4 rename 重命名表名
 
mysql> rename table test to people;
Query OK, 0 rows affected (0.01 sec)
再次查看表格,发现表名已改变:
 
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| people |
+----------------+
1 row in set (0.00 sec)
2.5 create 利用已有数据创建新表
 
mysql> create table newpeople select * from people;
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
查看数据库存在的表发现已经有了:
 
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| newpeople |
| people |
+----------------+
2 rows in set (0.00 sec)
3、数据的操作及管理
 
3.1 增加数据(增)
 
mysql> insert into people values(null,'Anny',22,'1990-09-09');
Query OK, 1 row affected (0.00 sec)
用select查询:
 
mysql> select * from people;
+----+------+-----+---------------------+
| id | name | age | birthday |
+----+------+-----+---------------------+
| 1 | Anny | 22 | 1990-09-09 00:00:00 |
+----+------+-----+---------------------+
1 row in set (0.00 sec)
3.2 删除数据(删)
 
mysql> delete from people where name='Anny';
Query OK, 1 row affected (0.00 sec)
再用select查询,发现没有删除的数据了:
 
mysql> select * from people;
+----+------+-----+---------------------+
| id | name | age | birthday |
+----+------+-----+---------------------+
| 2 | Lisa | 20 | 1992-09-09 00:00:00 |
+----+------+-----+---------------------+
1 row in set (0.00 sec)
3.3 修改数据(改)
 
mysql> update people set name='Anny' where name='Lisa';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
再查数据可以看到Lisa名字变为anny了:
 
mysql> select * from people;
+----+------+-----+---------------------+
| id | name | age | birthday |
+----+------+-----+---------------------+
| 2 | Anny | 20 | 1992-09-09 00:00:00 |
+----+------+-----+---------------------+
1 row in set (0.00 sec)
3.4 查询数据(查)
 
最简单的就是下面的语句:
 
mysql> select * from people;
+----+------+-----+---------------------+
| id | name | age | birthday |
+----+------+-----+---------------------+
| 2 | Anny | 20 | 1992-09-09 00:00:00 |
+----+------+-----+---------------------+
1 row in set (0.00 sec)
* 表示所有字段,也可以指定字段查询,如下:
 
mysql> select name from people;
+------+
| name |
+------+
| Anny |
+------+
1 row in set (0.00 sec)
4、管理视图
 
4.1 创建视图
 
mysql> create view people_view(name,age) as select name,age from people;
Query OK, 0 rows affected (0.00 sec)
创建成功后可以查看视图:
 
mysql> select * from people_view;
+------+-----+
| name | age |
+------+-----+
| Anny | 20 |
+------+-----+
1 row in set (0.00 sec)
可以用desc 查看视图字段:
 
mysql> desc people_view;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name | varchar(20) | NO | | NULL | |
| age | int(11) | NO | | NULL | |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
4.2 替换视图
 
创建或替换原有视图:
 
mysql> create or replace view people_view (id,name,age) as select id,name,age from people;
Query OK, 0 rows affected (0.00 sec)
查看现有视图:
 
mysql> select * from people_view;
+----+------+-----+
| id | name | age |
+----+------+-----+
| 2 | Anny | 20 |
| 3 | Lisa | 22 |
+----+------+-----+
2 rows in set (0.00 sec)
4.3 操作视图
 
当视图有变化时,对应的表格也会跟着改变,即操作视图就是操作表格,我们在视图中插入一条数据:
 
mysql> insert into people_view values('Lisa',22);
Query OK, 1 row affected (0.08 sec)
插入成功后,我们查看视图数据:
 
mysql> select * from people_view;
+------+-----+
| name | age |
+------+-----+
| Anny | 20 |
| Lisa | 22 |
+------+-----+
2 rows in set (0.00 sec)
可以看到视图中已经有了,再查看我们表格数据:
 
mysql> select * from people;
+----+------+-----+---------------------+
| id | name | age | birthday |
+----+------+-----+---------------------+
| 2 | Anny | 20 | 1992-09-09 00:00:00 |
| 3 | Lisa | 22 | NULL |
+----+------+-----+---------------------+
2 rows in set (0.00 sec)
发现也有了对应的数据
 
4.4 删除视图:
 
mysql> drop view people_view;
Query OK, 0 rows affected (0.00 sec)
到此,相信大家对“MySQL管理数据库、数据表、数据的基本操作是什么”有了更深的了解,不妨来实际操作一番吧!

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