SELECT * FROM table t1 WHERE t1.id=
(SELECT MAX(id) FROM table t2 WHERE t2.id<21)SELECT * FROM table t1 WHERE t1.id=
(SELECT MIN(id) FROM table t2 WHERE t2.id>21)
(SELECT MAX(id) FROM table t2 WHERE t2.id<21)SELECT * FROM table t1 WHERE t1.id=
(SELECT MIN(id) FROM table t2 WHERE t2.id>21)
FROM `guga`
WHERE abs( id - 9 ) =1
ORDER BY id得出的 第一条就是 上一条,第二条就是下一条