Sql 映射文件

1、连接DB数据库的参数来自properties对象

  public SqlSessionFactory build(InputStream inputStream, Properties properties) {
    return build(inputStream, null, properties);
  }

2、<resultmap>标签

  表中字段的名称和实体类中属性的名称不一致

	<resultMap type="entity.Userinfo" id="userinfo">
		<result column="id" property="idghy" />
		<result column="username" property="usernameghy" />
		<result column="password" property="passwordghy" />
		<result column="age" property="ageghy" />
		<result column="insertdate" property="insertdateghy" />
	</resultMap>

3、<sql>标签

 解决sql语句重复的问题

4、将sql 语句作为字符串变量传入