oracle,sqlserver,mysql区别

排序取数据

salserver:
select top 1 * from message m order by m.createTime desc         // 从排序后的数据中去除第一条  
oracle: rownum关键字或row_number函数
select * from (select mt.*, rownum rn from (select * from myTable) mt where rownum<=10) where rn >= 6      
mysql:
select * from message m,attention a where m.fromUserName = a.openid order by m.createTime desc limit 0,1  // 从索引为0开始取1条数据