oracle中 row_number() over()分析函数 + 行转列PIVOT DECODE函数 用法实例

这里主要说一下row_number() over()函数，PIVOT和DECODE函数会在接下来的练习中加入。首先说一下ROW_NUMBER() OVER(PARTITION BY COL1 ORDER BY COL2)。该函数表示根据col1分组，在分组内根据col2进行排序。函数的计算值就表示每组内部排序后的顺序编号（组内连续唯一）。

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首先准备测试数据

WITH temp AS
(
  SELECT 10 sId,'小李' sName,'男' sSex,'数学' subject,85 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'语文' subject,93 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'英语' subject,90 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'语文' subject,95 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'数学' subject,63 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'英语' subject,96 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'语文' subject,99 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'数学' subject,73 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'英语' subject,88 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'英语' subject,86 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'数学' subject,92 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'语文' subject,90 score FROM dual 
)
SELECT *
FROM temp r

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求出每个学生的成绩，科目在列头显示（行转列操作）

使用DECODE函数，进行行转列操作。

WITH temp AS
(
  SELECT 10 sId,'小李' sName,'男' sSex,'数学' subject,85 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'语文' subject,93 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'英语' subject,90 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'语文' subject,95 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'数学' subject,63 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'英语' subject,96 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'语文' subject,99 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'数学' subject,73 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'英语' subject,88 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'英语' subject,86 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'数学' subject,92 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'语文' subject,90 score FROM dual 
)
SELECT r.sId,r.sName,r.sSex
,SUM(DECODE(r.subject,'语文',r.score,NULL)) 语文
,SUM(DECODE(r.subject,'数学',r.score,NULL)) 数学
,SUM(DECODE(r.subject,'英语',r.score,NULL)) 英语
FROM temp r
GROUP BY r.sId,r.sName,r.sSex

使用PIVOT函数，进行行转列操作。

WITH temp AS
(
  SELECT 10 sId,'小李' sName,'男' sSex,'数学' subject,85 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'语文' subject,93 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'英语' subject,90 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'语文' subject,95 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'数学' subject,63 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'英语' subject,96 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'语文' subject,99 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'数学' subject,73 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'英语' subject,88 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'英语' subject,86 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'数学' subject,92 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'语文' subject,90 score FROM dual 
)
SELECT * FROM
(
  SELECT sId,sName,score,subject FROM temp
)
PIVOT
(
  SUM(score) FOR subject IN('语文' 语文,'数学' 数学,'英语' 英语)
)

求出每门课程的成绩排名（按照成绩由高到低排序）

WITH temp AS
(
  SELECT 10 sId,'小李' sName,'男' sSex,'数学' subject,85 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'语文' subject,93 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'英语' subject,90 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'语文' subject,95 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'数学' subject,63 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'英语' subject,96 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'语文' subject,99 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'数学' subject,73 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'英语' subject,88 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'英语' subject,86 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'数学' subject,92 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'语文' subject,90 score FROM dual 
)
SELECT r.subject,r.sId,r.sName,r.sSex,r.score,
ROW_NUMBER() OVER (PARTITION BY r.subject ORDER BY r.score DESC) rn
FROM temp r 

求出每门课程的成绩排名的前两名

WITH temp AS
(
  SELECT 10 sId,'小李' sName,'男' sSex,'数学' subject,85 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'语文' subject,93 score FROM dual UNION ALL
  SELECT 10 sId,'小李' sName,'男' sSex,'英语' subject,90 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'语文' subject,95 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'数学' subject,63 score FROM dual UNION ALL
  SELECT 11 sId,'小欣' sName,'男' sSex,'英语' subject,96 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'语文' subject,99 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'数学' subject,73 score FROM dual UNION ALL
  SELECT 12 sId,'小张' sName,'男' sSex,'英语' subject,88 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'英语' subject,86 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'数学' subject,92 score FROM dual UNION ALL
  SELECT 13 sId,'小萌' sName,'男' sSex,'语文' subject,90 score FROM dual 
)
SELECT * FROM 
(
  SELECT r.subject,r.sId,r.sName,r.sSex,r.score,
  ROW_NUMBER() OVER (PARTITION BY r.subject ORDER BY r.score DESC) rn
  FROM temp r
) WHERE rn <= 2