mybatis-基礎篇-UserMapper.xml

<!-- 引入dtd -->
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">




<!-- namespace就是包名加類名 -->
<mapper namespace="cn.dao.UserMapper">
<!-- id是一個方法，id是唯一的 -->
<!-- resaultType是返回值類型 -->
<select id="count" resultType="int">
<!-- 寫SQL語句 -->
select count(1) from user
</select>
</mapper>