在实际开发中经常会遇到计算某个字段的排名的情况

如下表：totak_sales

现在又如此要求：按sales的逆序排序，要求添加一个sales_rank字段，显示排名顺序

方法：

 代码如下: SELECT a1.Name, a1.Sales, COUNT(a2.sales) Sales_RankFROM Total_Sales a1, Total_Sales a2WHERE a1.Sales <= a2.Sales or (a1.Sales=a2.Sales and a1.Name = a2.Name)GROUP BY a1.Name, a1.SalesORDER BY a1.Sales DESC, a1.Name DESC;

结果：

或：

代码如下: SELECT a1.Name, a1.Sales, COUNT(a2.sales) Sales_RankFROM Total_Sales a1, Total_Sales a2WHERE a1.Sales < a2.Sales or (a1.Sales=a2.Sales and a1.Name = a2.Name)GROUP BY a1.Name, a1.SalesORDER BY a1.Sales DESC, a1.Name DESC;

结果：

由上面的方案，我们可以继续推测，如何选出某项来呢？

比如排名为5的那项内容：

代码如下: SELECT * from(SELECT a1.Name, a1.Sales, COUNT(a2.sales) Sales_RankFROM Total_Sales a1, Total_Sales a2WHERE a1.Sales < a2.Sales or (a1.Sales=a2.Sales and a1.Name = a2.Name)GROUP BY a1.Name, a1.SalesORDER BY a1.Sales DESC, a1.Name DESC) as tab WHERE tab.sales_rank=5;