text: --
  -- @lc app=leetcode id=626 lang=mysql
  --
  -- [626] Exchange Seats
  --
  -- https://leetcode.com/problems/exchange-seats/description/
  --
  -- database
  -- Medium (55.75%)
  -- Likes:    248
  -- Dislikes: 212
  -- Total Accepted:    37.4K
  -- Total Submissions: 63.9K
  -- Testcase Example:  '{"headers": {"seat": ["id","student"]}, "rows": {"seat": [[1,"Abbot"],[2,"Doris"],[3,"Emerson"],[4,"Green"],[5,"Jeames"]]}}'
  --
  -- Mary is a teacher in a middle school and she has a table seat storing
  -- students' names and their corresponding seat ids.
  -- The column id is continuous increment.
  -- 
  -- 
  -- Mary wants to change seats for the adjacent students.
  -- 
  -- 
  -- Can you write a SQL query to output the result for Mary?
  -- 
  -- 
  -- 
  -- 
  -- +---------+---------+
  -- |    id   | student |
  -- +---------+---------+
  -- |    1    | Abbot   |
  -- |    2    | Doris   |
  -- |    3    | Emerson |
  -- |    4    | Green   |
  -- |    5    | Jeames  |
  -- +---------+---------+
  -- 
  -- For the sample input, the output is:
  -- 
  -- 
  -- 
  -- 
  -- +---------+---------+
  -- |    id   | student |
  -- +---------+---------+
  -- |    1    | Doris   |
  -- |    2    | Abbot   |
  -- |    3    | Green   |
  -- |    4    | Emerson |
  -- |    5    | Jeames  |
  -- +---------+---------+
  -- 
  -- 
  -- Note:
  -- If the number of students is odd, there is no need to change the last one's
  -- seat.
  -- 
  --
  
  -- @lc code=start
  # Write your MySQL query statement below
  SELECT
    CASE
      WHEN seat.id % 2 = 1 AND seat.id = (SELECT COUNT(*) FROM seat) THEN seat.id
      WHEN seat.id % 2 = 0 THEN seat.id - 1
      ELSE seat.id + 1
    END AS id,
    student
  FROM seat
  ORDER BY id ASC
  ;
  -- @lc code=end
  
  