当在查询的时候需要传入多个参数的时候该怎么办呢:
1,封装成一个Model对象,底层HashMap还是一个
User user=new User(); user.setUserName("zhangsan"); user.setPassword("123456"); queryUserByuserNameAndPass(user);//为返回值类型为User
<select id="queryUserByuserNameAndPass" resultType="User" parameterType="com.j1.User" > select * from user u where u.user_name=#{userName} and u.pass_word=#{passWord} </select>
2,使用HashMap封装
//使用HashMap定义: HashMap <String,Object> map=new HashMap<String,Object>(); map.put("userName","zhangsan"); map.put("password","123456"); queryUserByuserNameAndPass(map);//为返回值类型为User
//sql 如下:
<select id="queryUserByuserNameAndPass" resultType="User" parameterType="Map" > select * from user u where u.user_name=#{userName} and u.pass_word=#{passWord} </select>
3,使用注解,@param
queryUserByuserNameAndPass(@param(''userName")String userName,@param("password")String password)
<select id="queryUserByuserNameAndPass" resultType="User"> select * from user u where u.user_name=#{userName} and u.pass_word=#{passWord}// </select>
queryUserByuserNameAndPass(String userName,String PassWord); //返回值类型为Usre
//sql
<select id="queryUserByuserNameAndPass" resultType="User"> select * from user u where u.user_name=#{userName} and u.pass_word=#{passWord}//会报错的 </select>
改为如下:
<select id="queryUserByuserNameAndPass" resultType="User"> select * from user u where u.user_name=#{0} and u.pass_word=#{1}//运行成功但是,可读性不高 </select>
//parameterType 参数类型可以是基本数据类型(int,String,long),可以是Model对象,也可以是Map;
1,基本数据类型:
//java代码 @Override
public void deleteUserById(Long id) {
SqlSession sqlSession = sqlSessionFactory.openSession(true);
sqlSession.delete("cn.itcast.mybatis.user.deleteUserById", id);
}
//sql
<delete id="deleteUserById" parameterType="java.lang.Long">
DELETE FROM tb_user WHERE id = #{id}
</delete>
2,Model对象
//java代码: @Override
public void saveUser(User user) {
SqlSession sqlSession = sqlSessionFactory.openSession(true);
sqlSession.insert("cn.itcast.mybatis.user.saveUser", user);
} @Override
public void updateUser(User user) {
SqlSession sqlSession = sqlSessionFactory.openSession(true);
sqlSession.update("cn.itcast.mybatis.user.updateUser", user);
}
//sql
<update id="updateUser" parameterType="cn.itcast.mybatis.pojo.User">
UPDATE tb_user
SET
password = #{password},
name = #{name},
age = #{age},
sex = #{sex},
birthday = #{birthday},
updated = NOW()
WHERE
id = #{id};
</update>
3.map
//java HashMap <String,Object> map=new HashMap<String,Object>(); map.put("userName","zhangsan"); map.put("password","123456"); queryUserByuserNameAndPass(map);//为返回值类型为User
//sql 如下:
<select id="queryUserByuserNameAndPass" resultType="User"> select * from user u where u.user_name=#{userName} and u.pass_word=#{passWord}// </select>