oracle – 如何在条件下找到两行之间的差异

name      point
----------
steve     207
Mary      203
steve     205
steve     200
steve     139
Mary      300

我想得到条件eqn = [(第1行) – 行]的行之间的差异,其中name = steve,所以我理想地希望它是,

steve 2   //207 - 0
steve 5   //205 - 207
steve 61  //200 - 205
steve 139 //139 - 200

有代码可以找到连续行之间的差异.但是添加条件时它不起作用.

解决方法

LAG可以帮助您：

select name,coalesce( 
        point - lag( point,1,Null ) over (order by point),point)
    as diff,point || '-' ||
    LEAD( point,0 ) over (order by point) as prev_point
  from t   
  where name = 'steve'  
  order by point desc

Results：

|  NAME | DIFF | PREV_POINT |
-----------------------------
| steve |    2 |      207-0 |
| steve |    5 |    205-207 |
| steve |   61 |    200-205 |
| steve |  139 |    139-200 |

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