数据库CRUD操作以及MyBatis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：
name:logub_ticket
lable:
id
user_id
ticket
expired
status
• 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"
<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>
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);
}
<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
