oracle字段去重，展示多列

oracle查詢多列時對單列去重

最近有一個查詢，需要針對查詢結果中的某一列進行去重，而又要得到想要的其他列。一開始就想到distinct去重，但是distinct去重的話針對查詢結果爲單列時有效，如果查詢的結果包括多列distinct會對所有列作用，得不到想要的結果。最後經過大佬請教學習到可以使用rank() over()來解決此問題。下面請看。

1. 查詢所有

select * from person;

• 1

2. 查詢單列去重

select distinct(pname) from person;

• 1

去重有效。

3. 查詢多列去重

select distinct(pname), pid,page from person;

• 1

去重失敗了。

4. 用rank() over()查詢

select a.*, rank() over(partition by a.pname order by pid) rn from person a

• 1
• 2

使用rank() over()後面多了一個數值，然後針對這個數值處理就行了

4. 用rank() over()查詢多列去重

select b.*
from(
  select a.*, rank() over(partition by a.pname order by pid) rn
  from person a) b 
where b.rn=1

• 1
• 2
• 3
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• 6

去重是不是成功了？給點個贊吧，謝謝！

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