我找到了一个代码来找到电影院的一致座位号。但我不明白什么是“头”，尤其是它的语法。谁能解释一下：头儿(我在谷歌上搜索了一下，但没有得到任何帮助。）非常感谢！

SELECT 
    s1.seat AS start_seat,
    '~',
    s2.seat AS end_seat
FROM 
    Seats s1, Seats s2 
WHERE 
    s2.seat = s1.seat + (:head_cnt -1 )
    AND NOT EXISTS ( SELECT 
                         *
                     FROM 
                         Seats s3
                     WHERE 
                         s3.seat BETWEEN s1.seat AND s2.seat
                         AND s3.status <> 'available')

这是原始表格：

CREATE TABLE Seats
( seat     INTEGER      NOT NULL,
  status   VARCHAR(32)  NOT NULL,
PRIMARY KEY(seat));

状态有两个值：“可用”或“保留”