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MySQL数据库常用操作

一、MySQL 常规命令

1)显示当前数据库的版本号和日期。

MariaDB [(none)]> select version(),current_date();
+----------------+----------------+
| version()      | current_date() |
+----------------+----------------+
| 5.5.60-MariaDB | 2018-08-29     |
+----------------+----------------+
1 row in set (0.00 sec)

2)通过 AS 关键字设置字段名。

SELECT VERSION() AS name; //可设置中文，通过单引号
select 字段 as 字段别名;
例如：select version() as '版本号';
MariaDB [(none)]> select version() as '版本号';
+----------------+
| 版本号         |
+----------------+
| 5.5.60-MariaDB |
+----------------+
1 row in set (0.00 sec)

3)通过 SELECT 执行返回计算结果

MariaDB [(none)]> select (20+5)*4;
+----------+
| (20+5)*4 |
+----------+
|      100 |
+----------+
1 row in set (0.00 sec)

4)通过多行实现数据库的使用者和日期

MariaDB [(none)]> select
    -> user()
    -> ,
    -> now()
    -> ;
+----------------+---------------------+
| user()         | now()               |
+----------------+---------------------+
| root@localhost | 2018-08-29 21:59:39 |
+----------------+---------------------+
1 row in set (0.00 sec)

5)通过一行显示数据库使用者和日期

MariaDB [(none)]> select user();select now();
+----------------+
| user()         |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)

+---------------------+
| now()               |
+---------------------+
| 2018-08-29 22:01:49 |
+---------------------+
1 row in set (0.00 sec)

6)命令的取消

MariaDB [(none)]> show database
    -> \c

7)MySQL 窗口的退出

MariaDB [(none)]> exit;
Bye
[root@centos ~]# 

MySQL 常用数据类型

• 整数型：TINYINT，SMALLINT，INT，BIGINT
• 浮点型：FLOAT，DOUBLE，DECIMAL(M,D)
• 字符型：CHAR，VARCHAR
• 日期型：DATETIME，DATE，TIMESTAMP
• 备注型：TINYTEXT，TEXT，LONGTEXT

二、MySQL 数据库操作

1)显示当前存在的数据库

MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| test               |
+--------------------+
4 rows in set (0.00 sec)

2)选择你所需要的数据库

MariaDB [(none)]> use test;
Database changed

3)查看当前所选择的数据库

MariaDB [test]> select database();
+------------+
| database() |
+------------+
| test       |
+------------+
1 row in set (0.00 sec)

4)根据数据库设置中文编码

MariaDB [test]> SET NAMES gbk; --set names utf8;
Query OK, 0 rows affected (0.00 sec)

5)查看有多少张表

MariaDB [test]> show tables;
Empty set (0.00 sec)

6)查看一张表的所有内容

MariaDB [test]> select now() from dual;
+---------------------+
| now()               |
+---------------------+
| 2018-08-29 22:16:05 |
+---------------------+
1 row in set (0.00 sec)

7)创建一个数据库

MariaDB [test]> create database book;
Query OK, 1 row affected (0.00 sec)

8)在数据库里创建一张表

MariaDB [book]> create table users(
    -> username varchar(20) not null,
    -> sex char(1),
    -> birth datetime
    -> );
Query OK, 0 rows affected (0.01 sec)

9)显示表的结构

MariaDB [book]> desc users; --describe users;
+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(20) | NO   |     | NULL    |       |
| sex      | char(1)     | YES  |     | NULL    |       |
| birth    | datetime    | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

10)给表插入一条数据

MariaDB [book]> INSERT INTO users (username,sex,birth) VALUES ('Lee','x',NOW());
Query OK, 1 row affected (0.00 sec)

11)筛选指定的数据

MariaDB [book]> SELECT * FROM users WHERE username = 'Lee';
+----------+------+---------------------+
| username | sex  | birth               |
+----------+------+---------------------+
| Lee      | x    | 2018-08-29 22:20:38 |
+----------+------+---------------------+
1 row in set (0.00 sec)

12)修改指定的数据

MariaDB [book]> UPDATE users SET sex = '男' WHERE username='Lee';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1

13)删除指定的数据

MariaDB [book]> DELETE FROM users WHERE username='Lee';
Query OK, 1 row affected (0.00 sec)

14)按指定的数据排序

MariaDB [book]> SELECT * FROM users ORDER BY birth DESC; --正序
Empty set (0.00 sec)

15)删除指定的表

MariaDB [book]> DROP TABLE users;
Query OK, 0 rows affected (0.00 sec)

MariaDB [book]> show tables;
Empty set (0.00 sec)

16)删除指定的数据库

MariaDB [book]> drop database book;
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> 

三、MySQL 常用函数

文本函数

数字函数

日期和时间函数

格式化日期和时间(DATE_FORMAT()和TIME_FORMAT())

转：MySQL数据库常用操作

MySQL数据库常用操作

标签：big   order   结构   delete   img   5.5   常用函数   中文编码   一个   

原文地址：https://www.cnblogs.com/hglibin/p/9557413.html