sql - 如何通过在oracle中获取重复记录来获取组后的唯一记录

Question

我正在尝试获取唯一记录但获取重复如何防止这种情况请帮助我代码如下：

SELECT a.EXAM_DEGREE_ID,a.MAJOR_GROUP_ID,a.INSTITUTION,a.BOARD,a.RESULT_GRADE,a.PASSING_YEAR,f.ELEMENT_URL
FROM student_acadimicinfo a
left join m00_lkpdata b on a.EXAM_DEGREE_ID=b.LKP_ID
left join m00_lkpdata c on a.MAJOR_GROUP_ID=c.LKP_ID
left join m00_lkpdata d on a.BOARD = d.LKP_ID
left join STUDENT_PERSONAL_INFO e on e.STUDENT_ID = a.STUDENT_ID
left join SKILL_DEV_ELEMENT f on f.APPLICANT_ID = e.APPLICANT_ID
WHERE a.STUDENT_ID ='341'
group by a.EXAM_DEGREE_ID,a.MAJOR_GROUP_ID,a.INSTITUTION,a.BOARD,a.RESULT_GRADE,a.PASSING_YEAR,f.ELEMENT_URL

结果：

谢谢

Answer 1

正如我所见，您提到的行不重复，因为它们具有不同的 ELEMENT_URL。您可以从 group by 中排除 ELEMENT_URL，并在聚合函数的帮助下决定该字段中显示的内容。例如：

SELECT a.EXAM_DEGREE_ID,a.MAJOR_GROUP_ID,a.INSTITUTION,a.BOARD,a.RESULT_GRADE,a.PASSING_YEAR, max(f.ELEMENT_URL)
FROM student_acadimicinfo a
left join m00_lkpdata b on a.EXAM_DEGREE_ID=b.LKP_ID
left join m00_lkpdata c on a.MAJOR_GROUP_ID=c.LKP_ID
left join m00_lkpdata d on a.BOARD = d.LKP_ID
left join STUDENT_PERSONAL_INFO e on e.STUDENT_ID = a.STUDENT_ID
left join SKILL_DEV_ELEMENT f on f.APPLICANT_ID = e.APPLICANT_ID
WHERE a.STUDENT_ID ='341'
group by a.EXAM_DEGREE_ID,a.MAJOR_GROUP_ID,a.INSTITUTION,a.BOARD,a.RESULT_GRADE,a.PASSING_YEAR