需要获得客户明智的销售记录与当前日期和以前的日期

Question

要求是获取具有当前日期和上一个日期的客户销售记录。任何人都可以帮助我使用SQL获取数据。

下表是来源：

Name    Order   Sales date
Ann     1       13/01/2017
Ann     3       26/01/2017
Ann     6       14/03/2017
Ben     2       16/01/2017
Ben     5       21/02/2017
Cavin   4       15/03/2017

目标应为

Name    Order   latest_sales_date   previous_sales_date
Ann     1       13/01/2017  
Ann     3       26/01/2017          13/01/2017
Ann     6       14/03/2017          26/01/2017
Ben     2       16/01/2017  
Ben     5       21/02/2017          16/01/2017
Cavin   4       15/03/2017  

Answer 1

使用ANSI标准lag()功能：

select t.*,
       lag(sales_date) over (partition by name order by sales_date) as prev_sales_date
from t;

Answer 2

使用Oracle，Postgres或SQL Server 2012以后：

select t1.Name, t1.Order, t1.Sales_date as latest_sale, 
       lag(t1.Sales_Date) over (partition by t1.Name order by t1.Order) as previous_sales_date
from MyTable t1