Mybatis - CURD（01）

返回值为集合类型

<!-- 占位符#{} 类似于JBDC的占位符，比如上面的sql语句，传入Integer10时，它就是把Integer10填在占位符的位置如果是String10，就是把String10填在里面。里面的参数可以随便填，但不能为空。${} 字符串拼接，如下面的sql语句，传入"五"，最终注入数据库的是"%五%"。里面的参数只能写value#{} 占位符实现字符串拼接，"%${value}%" <==> "%"#{v}"%"-->
<select id="findUsersByName" parameterType="String" resultType="com.pojo.User">select * from user where username like "%${value}%"
</select>

//1、加载核心配置文件
String coreXml = "sqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(coreXml);
//2、创建工厂
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
//3、获得sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
//4、执行sql语句
List<User> users = sqlSession.selectList("User.findUsersByName", "五");
//5、处理结果
System.out.println(users);

插入

<!-- 这里的 #{} 参数不能再随便写了，需要取出来User里的属性-->
<insert id="insert" parameterType="com.pojo.User">insert into user(username, sex, birthday, address) values(#{username}, #{sex}, #{birthday}, #{address});
</insert>

public void insert() throws Exception {//1、加载核心配置文件String coreXml = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(coreXml);//2、创建工厂SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//3、获得sqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//4、执行sql语句User user = new User("helloworld", "2", new Date(), "aaaaaa");int i = sqlSession.insert("User.insert", user);//默认是不自动提交事务sqlSession.commit();//5、处理结果System.out.println(i);
}

插入数据时返回主键

<insert id="insert" parameterType="com.pojo.User"><!-- 返回最新插入的id，底层是mysql提供 --><!-- Integer类型，自增长是先保存数据再生成ID，比如uuid，会先生成ID，再保存数据 --><selectKey keyProperty="id" resultType="Integer" order="AFTER">select LAST_INSERT_ID()</selectKey>insert into user(username, sex, birthday, address) values(#{username}, #{sex}, #{birthday}, #{address});
</insert>

public void insert() throws Exception {//1、加载核心配置文件String coreXml = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(coreXml);//2、创建工厂SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//3、获得sqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//4、执行sql语句User user = new User("helloworld", "2", new Date(), "aaaaaa");int i = sqlSession.insert("User.insert", user);//默认是不自动提交事务sqlSession.commit();//5、处理结果System.out.println(user.getId());
}

更新用户

<update id="updateUser" parameterType="com.pojo.User">update user set username = #{
   username}, sex = #{
   sex}, birthday = #{
   birthday}, address = #{
   address}where id = #{
   id}
</update>

@org.junit.Test
public void update() throws Exception {//1、加载核心配置文件String coreXml = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(coreXml);//2、创建工厂SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//3、获得sqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//4、执行sql语句User user = new User("helloworld", "1", new Date(), "aaaaaa");user.setId(1);int i = sqlSession.update("User.updateUser", user);//默认是不自动提交事务sqlSession.commit();//5、处理结果
}

删除

<update id="delete" parameterType="Integer">delete from user where id = #{aaa}
</update>

@org.junit.Test
public void delete() throws Exception {//1、加载核心配置文件String coreXml = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(coreXml);//2、创建工厂SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//3、获得sqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//4、执行sql语句User user = new User("helloworld", "1", new Date(), "aaaaaa");user.setId(1);int i = sqlSession.delete("User.delete", 28);//默认是不自动提交事务sqlSession.commit();//5、处理结果
}