Question

问题是，第2行的StudentId应该为1，因为他们的姓名和父亲姓名相同。同样，由于姓名和父亲姓名相同，第4行的StudentId应该为3

我已根据我的要求修改了查询，因为当Student_name，Student dob，student父亲，email countryId和skype id相同时，我必须更新我的student_id，现在更新的查询将是

  Merge into student_new_Backup
     using ( select min(student_id) as stid, student_name, student_father,student_dob,email_id,skype_id,country
             from student_new_Backup 
              group by student_name, student_father,student_dob,email_id,skype_id,country) a
     on (student_new_Backup.student_name= a.student_name
          and student_new_Backup.student_father=a.student_father
          and student_new_Backup.student_dob=a.student_dob
unfortunately no student_id is update
          and student_new_Backup.email_id=a.email_id
          and student_new_Backup.skype_id=a.skype_id
          and student_new_Backup.country=a.country)
      when matched then 
           UPDATE SET student_new_Backup.student_id=a.stid
           ;
           commit;

不幸的是，没有Student_id是最新的

Answer 1

我想你想要

update t
    set studentId = (select min(t2.studentId)
                     from t t2
                     where t2.name = t.name and t2.fathername = t.fathername
                    );

编辑：

如果您想要NULL安全比较，则需要明确：

update t
    set studentId = (select min(t2.studentId)
                     from t t2
                     where (t2.name = t.name or t2.name is null and t.name is null) and
                           (t2.fathername = t.fathername or t2.fathername is null and t.fathername is null)
                    );

Answer 2

您可以使用合并进行更新

 Merge into table_name
 using ( select min(studentId) as stid, Name, fathername
         from table_name 
          group by Name, fathername) a
 on (table_name.Name= a.Name
      and table_name.fatherName=a.fatherName)
  when matched then 
       UPDATE SET table_name.studentId=a.stid

online demo

当其他列值相同时更新列值

2 个答案: