SQL与NoSQL、数据库重要概念、SQL的基本语句
SQL与NoSQL
数据库服务端可以服务多种类型的客户端
客户端可以是自己开发的，也可以是python代码编写的，也可以是其他编程语言编写的
Tips:
- SQL有时又也指代关系型数据库
- NoSQL有时候也指代非关系型数据库
数据库重要概念
为了更方便的理解数据库的概念，将数据库分成了下列三种表述方式
基本SQL语句
1、基于库-CRUD
- 创建库
create database 库名
mysql> create database userinfor;
Query OK, 1 row affected (0.00 sec)
- 查看库
- 查看所有库:show databases
- 查看指定库:show create database 库名
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| userinfor |
+--------------------+
5 rows in set (0.00 sec)
########################################################
show create database userinfor;
---------------------------------------
mysql> show create database userinfor;
+-----------+----------------------------------------------------------------------+
| Database | Create Database |
+-----------+----------------------------------------------------------------------+
| userinfor | CREATE DATABASE `userinfor` /*!40100 DEFAULT CHARACTER SET latin1 */ |
+-----------+----------------------------------------------------------------------+
1 row in set (0.00 sec)
- 编辑库
- alter database 库名 charset='utf8';
mysql> alter database userinfor charset='utf8';
Query OK, 1 row affected (0.02 sec)
- 切换库
use 库名
mysql> use userinfo;
Database changed
2、基于表-CRUD
我们对表进行操作之前必须先确定我们要操作的是哪个表
- 创建表
create table 表名（字段名1 字段类型，字段名2 字段类型，..）
mysql> create table t1(name varchar(24),age int, gender varchar(23));
Query OK, 0 rows affected (0.01 sec)
- 查看表
mysql> show tables;
+--------------------+
| Tables_in_userinfo |
+--------------------+
| t1 |
| t2 |
| t3 |
| t4 |
| t6 |
+--------------------+
5 rows in set (0.00 sec)
mysql> show create table t1;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table
|
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
| t1 | CREATE TABLE `t1` (
`name` varchar(24) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`gender` varchar(23) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> desc t1;
+--------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| name | varchar(24) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| gender | varchar(23) | YES | | NULL | |
+--------+-------------+------+-----+---------+-------+
3 rows in set (0.02 sec)
- 编辑表
- alter table 表名 rename 新表名
mysql> alter table t6 rename t5;
Query OK, 0 rows affected (0.00 sec)
mysql> drop table t5;
Query OK, 0 rows affected (0.00 sec)
3、基于记录-CRUD
- 插入记录
insert into 表名 values(数据值1，数据值2, ...)
mysql> insert into t1 values('kangkang', 18 ,'male'),('lizhi', 18 ,'male');
Query OK, 1 row affected (0.01 sec)
- 查询记录
mysql> select * from userinfo.t1;
+----------+------+--------+
| name | age | gender |
+----------+------+--------+
| kangkang | 18 | male |
| lizhi | 18 | male |
+----------+------+--------+
- 编辑数据
- update 表名 set 字段名=新数据 where 赛选条件
mysql> update t1 set name='kangk' where name='kangkang';
Query OK, 1 row affected (0.02 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> delete from t1;
Query OK, 2 rows affected (0.00 sec)
mysql> select * from userinfo.t1;
Empty set (0.00 sec)
- delete from 表名 where 筛选条件
mysql> delete from t1 where name='lizhi';
Query OK, 1 row affected (0.00 sec)
