oracle row_number() over(partition by .. order by ..)和rank() over(partition by .. order by ..) 和dens

新建一個測試表

create table dim_ia_test2(device_number varchar2(20),desc2 varchar2(20))

插入數據後獲得：

1、oracle row_number() over(partition by .. order by ..)

只以電話號碼排序，默認升序

select device_number,desc2,row_number() over(order by device_number ) rn from dim_ia_test2;

以電話號碼分組，並排序

select device_number,desc2,row_number() over(partition by device_number order by device_number ) rn from dim_ia_test2;

row_number的排序特色爲順序排

2、rank() over(partition by .. order by ..)

select device_number,desc2,rank() over(order by device_number ) rn from dim_ia_test2;

select device_number,desc2,rank() over(partition by device_number  order by device_number ) rn from dim_ia_test2;

3、dense_rank() over(partition by .. order by ..)

select device_number,desc2,dense_rank() over(order by device_number ) rn from dim_ia_test2;

select device_number,desc2,dense_rank() over(partition by device_number order by device_number ) rn from dim_ia_test2;

以上是三個排序的開窗函數，row_number() over(partition by .. order by ..)因爲是順序排序，分組和排序都比較有意義；

rank() over(partition by .. order by ..)排序是跳躍的，排序比較有意義；

和dense_rank() over(partition by .. order by ..)排序是順序的，排序比較有意義；