返回其旁边具有特定记录的所有记录

Question

我几乎没有按序列号排序的记录，我需要所有记录，以便一个记录后跟另一个满足给定条件的记录。

学生表 -> CREATE TABLE 学生（sno int, id int, firstname varchar(255));

条件：记录应该有 firstname = "alex"，并且后面必须有 firstname = "justin" 的记录

Input: 
    sno id firstname
    1   1   alex
    2   2   justin
    3   1   alex
    4   3   Seth
    5   2   justin
    6   1   alex
    7   2   justin
    8   2   justin

Output: 
    sno id firstname
    1   1   alex
    2   2   justin
    6   1   alex
    7   2   justin
    

Answer 1

你可以使用lead()/lag():

select s.*
from (select s.*,
             lag(name) over (order by sno) as prev_name,
             lead(name) over (order by sno) as next_name
      from student s
     ) s
where (name = 'alex' and next_name = 'justin') or
      (name = 'justin' and prev_name = 'alex')