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: 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 "-// 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>       3. 官网： 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