如何从复合主键表中选择*

Question

我了解了如何选择与复合主键表不同的方法 ：

; with temp as (
 select row_number() over (partition by First_PK order by Second_PK desc)
   as row_num, First_PK, Second_PK, data
 from test)
 select * from temp
 where row_num = 1

但是我现在面临另一个问题，而不是where row_num = 1我想拥有where row_num = MAX （我的意思是最大值）

如何选择与组合主键表不同

Answer 1

由于一个排序顺序的最后一行将是相反排序顺序的第一行，因此您只需在窗口函数row_number更改order by子句以使用升序：

; with temp as (
 select row_number() over (partition by First_PK order by Second_PK)
   as row_num, First_PK, Second_PK, data
 from test)
 select * from temp
 where row_num = 1

Answer 2

解决方案是：

; with temp as (
 select row_number() over (partition by First_PK order by Second_PK)
   as row_num, First_PK, Second_PK, data
 from test)
 select * from temp
 WHERE row_num=(SELECT max(row_num) FROM temp);