数据库CRUD操作以及MyBatisd的配置使用

• 业务字段设计

• 数据库创建

• CRUD操作

• MyBatis集成

• 注解和XML定义

• ViewObject和DateTool

• 首页开发

 

 

• 业务字段设计

实体：

• 数据库创建

GUI版本管理工具创建，然后通过GUI转SQL；

• CRUD操作

 

insert into table_name (列1, 列2,...) VALUES (值1, 值2,....)；

select 列名1，列名2 from 表名称 where 条件；

条件： between 1 and 2 order by 3 desc

UPDATE 表名称 SET 列名称 = 新值 WHERE 列名称 = 某值

 

• MyBatis集成

1. application.properties增加spring配置数据库链接地址

spring.datasource.url = jdbc:mysql://localhost:3306/wenda?useUnicode=true&characterEncoding=utf8&useSSL=false

spring.datasource.username = root

spring.datasource.password = qwertyuiop

mybatis.config-location = classpath:mybatis-config.xml

同时：在配置的同级别目录下：resources/templates建立粘贴建立官网有：mybatis-config.xml

<? xml version ="1.0" encoding ="UTF-8" ?>

<!DOCTYPE configuration

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd" >

< configuration >

 

< settings >

<!-- Globally enables or disables any caches configured in any mapper under this configuration -->

< setting name ="cacheEnabled" value ="true" />

<!-- Sets the number of seconds the driver will wait for a response from the database -->

< setting name ="defaultStatementTimeout" value ="3000" />

<!-- Enables automatic mapping from classic database column names A_COLUMN to camel case classic Java property names aColumn -->

< setting name ="mapUnderscoreToCamelCase" value ="true" />

<!-- Allows JDBC support for generated keys. A compatible driver is required.

This setting forces generated keys to be used if set to true,

as some drivers deny compatibility but still work -->

< setting name ="useGeneratedKeys" value ="true" />

</ settings >

 

<!-- Continue going here -->

 

</ configuration >

2. pom.xml引入mybatis-spring-boot-starter和mysql-connector-java

<dependency>

<groupId> org.mybatis </groupId>

<artifactId> mybatis </artifactId>

<version>1.1.1 </version>

</dependency>

 

< dependency >

< groupId > mysql </ groupId >

< artifactId > mysql-connector-java </ artifactId >

< scope > runtime </ scope >

</ dependency >

 

 

 

3. 官网： http://www.mybatis.org/mybatis3/zh/index.html

DAO层建立modul相关的userDao来通过mybatis访问数据库库:

//注解配置；

@Mapper

public interface UserDAO {

String TABLE_NAME = "user" ;

String INSET_FIELDS = " name, password, salt, head_url " ;

String SELECT_FIELDS = " id, name, password, salt, head_url" ;

//通过抽象，实现crud的复用；

@Insert ( { "insert into " , TABLE_NAME , "(" , INSET_FIELDS ,

") values (#{name},#{password},#{salt},#{headUrl})" } )

int addUser ( User user ) ;

 

@Select ( { "select " , SELECT_FIELDS , " from " , TABLE_NAME , " where id=#{id}" } )

User selectById ( int id ) ;

 

@Select ( { "select " , SELECT_FIELDS , " from " , TABLE_NAME , " where name=#{name}" } )

User selectByName ( String name ) ;

 

@Update ( { "update " , TABLE_NAME , " set password=#{password} where id=#{id}" } )

void updatePassword ( User user ) ;

 

@Delete ( { "delete from " , TABLE_NAME , " where id=#{id}" } )

void deleteById ( int id ) ;

}

//xml配置，在相应的resources下建立DAO相应目录的的xml；

<mapper namespace="com.nowcoder.dao.QuestionDAO"> <sql id="table">question</sql> <sql id="selectFields">id,title, content,comment_count,created_date,user_id </sql> <select id="selectByUserIdAndOffset" resultType="com.nowcoder.model.Question"> SELECT <include refid="selectFields"/> FROM <include refid="table"/>

<if test="userId != 0"> WHERE user_id = #{userId} </if> ORDER BY id DESC LIMIT #{offset},#{limit} </select> </mapper>

 

 

• 注解和XML定义

• ViewObject和DateTool

• 首页开发