Oracle-分析函数之排序后顺序号row_number()

ROW_NUMBER() OVER (PARTITION BY COL1 ORDER BY COL2) 

name | seqno | description
A | 1 | xgj
A | 2 | xgj
A | 3 | xgj
A | 4 | xgj
B | 1 | xgj
B | 2 | xgj
B | 3 | xgj
B | 4 | xgj
C | 1 | xgj
C | 2 | xgj
C | 3 | xgj
C | 4 | xgj

A | 1 | xgj
A | 2 | xgj
B | 1 | xgj
B | 2 | xgj
C | 1 | xgj
C | 2 | xgj

select name, seqno, description
  from (select name,
               seqno,
               description,
               row_number() over(partition by name order by seqno) id
          from table_name)
 where id <= 3;