編寫一個 SQL 查詢來實現分數排名。如果兩個分數相同,則兩個分數排名(Rank)相同。請注意,平分後的下一個名次應該是下一個連續的整數值。換句話說,名次之間不應該有“間隔”。
+----+-------+ | Id | Score | +----+-------+ | 1 | 3.50 | | 2 | 3.65 | | 3 | 4.00 | | 4 | 3.85 | | 5 | 4.00 | | 6 | 3.65 | +----+-------+
例如,根據上述給定的 Scores
表,你的查詢應該返回(按分數從高到低排列):
+-------+------+ | Score | Rank | +-------+------+ | 4.00 | 1 | | 4.00 | 1 | | 3.85 | 2 | | 3.65 | 3 | | 3.65 | 3 | | 3.50 | 4 | +-------+------+
解法一:對於每一個分數,從表中找出有多少個大於或等於該分數的不重複分數,然後降序排列
select Score,
(select count(distinct Score) from Scores as s2 where s2.Score >= s1.Score) Rank
from Scores as s1
order by Score DESC;
解法二:使用聯結 join,當左表的分數小於等於右表的分數時,對右表的分數進行計數(即計算有幾個不重複的分數大於自己,計算結果就是rank),然後根據id分組後,再根據分數降序排列
select s1.Score, count(distinct s2.Score) Rank
from Scores as s1 join Scores as s2 on s1.Score <= s2.Score
group by s1.Id
order by s1.Score DESC;