INNER JOIN 连接两个数据表的用法：
SELECT * FROM 表1 INNER JOIN 表2 ON 表1.字段号=表2.字段号
inner join(等值连接) 只返回两个表中联结字段相等的行
//从t1表的全部字段和t2表中 READ_FLAG,和LOOK_FLAG字段进行展示
SELECT
t1.*,
t2.READ_FLAG,
t2.LOOK_FLAG
//从 表d_notice t1 和 表 d_notice_read_flag t2以条件 t1.row_id = t2.NOTICE_ID 进行查询
FROM
d_notice t1
INNER JOIN d_notice_read_flag t2
ON t1.row_id = t2.NOTICE_ID
WHERE t1.ALERT_FLAG = 0
AND t1.USE_FLAG = 1
AND t1.DEL_FLAG = 0
AND t2.READ_FLAG = 0
AND t2.LOOK_FLAG = 0
AND t2.USER_ACCOUNT = ?
AND t1.START_TIME < ?
AND t1.END_TIME > ?
ORDER BY t1.TOP_FLAG DESC,
t1.CREATE_TIME DESC
List<Map<String,Object>> findMapList = this.baseDao.findMapList(sql, userAccount, nowTime, nowTime);