Question

这是我第一次使用这样的论坛进行SQL帮助，所以请耐心等待！我有一个用于学生数据的大型查询集，每个学生都有一行，其中主要连接表是他们的应用程序记录（所有其他表加入到该应用程序记录中）。现在，我正在寻找学位数据，但是很多学生都有多个学位，因此它会重复学生行（嘘！）。

以下是它的缩写版本：

StudentID CohortTerm    DegreeYear  DegreeMonth  
1         2009 Spring   2011        05            
1         2009 Spring   2013        10            
2         2012 Fall     2015        05            
3         2015 Fall     2017        05            
3         2015 Fall     2018        05

这就是我想要的样子：

StudentID CohortTerm  Degree1_Y  Degree1_M  Degree2_Y  Degree2_M 
1         2009 Spring   2011        05      2013       10   
2         2012 Fall     2015        05            
3         2015 Fall     2017        05      2018       05

Answer 1

以下是使用分析函数执行此操作的另一种方法：

WITh test_data AS
(
 SELECT 1 StudentID, 2009 Cohort, 'Spring' Term, 2011 DegreeYear, '05' DegreeMonth FROM dual
  UNION ALL
 SELECT 1, 2009, 'Spring', 2013, '10' FROM dual    
  UNION ALL
 SELECT 2, 2012, 'Fall'  , 2015, '05' FROM dual    
  UNION ALL
 SELECT 3, 2015, 'Fall'  , 2017, '05' FROM dual     
  UNION ALL
 SELECT 3, 2015, 'Fall'  , 2018, '05' FROM dual         
 ) 
SELECT * FROM
 (
 SELECT ROW_NUMBER() OVER (PARTITION BY Cohort ORDER BY Cohort, DegreeYear, DegreeMonth) rno
 , StudentID, Cohort, Term, DegreeYear, DegreeMonth 
 , LEAD(DegreeYear)  OVER (PARTITION BY Cohort ORDER BY Cohort, DegreeYear, DegreeMonth) DegreeYear2
 , LEAD(DegreeMonth) OVER (PARTITION BY Cohort ORDER BY Cohort, DegreeYear, DegreeMonth) DegreeMonth2
  FROM test_data
)
WHERE rno = 1
ORDER BY Cohort, DegreeYear, DegreeMonth
/

输出：

RNO STUDENTID   COHORT  TERM    DEGREEYEAR  DEGREEMONTH DEGREEYEAR2 DEGREEMONTH2
1         1      2009   Spring      2011         05         2013        10
1         2      2012   Fall        2015         05     
1         3      2015   Fall        2017         05          2018       05

Answer 2

正如其他人评论的那样，pivot正是您所寻找的。请在此处查看pivot docs。

将sql行重组为相同类型的列

2 个答案: