我使用MYSQL和正在尋找一種方式，只選擇一排它過去和下一行有一個叫做fav_num以「3」我可以選擇具有條件的行嗎？上一行和下一行有條件嗎？
的值。例如我場有6行和兩個字段。這些字段是ID和fav_number。
ID| fav_num
1 | 3
2 | 2
3 | 3
4 | 7
5 | 2
6 | 9
我想找到一種方法，從那裏以前和下一行有3 一個fav_num表返回ID，然後在此查詢將返回ID 2.
如果我道歉我的問題聽起來很混亂。
我覺得這可能是工作..
SELECT id
FROM tab t
WHERE t.id BETWEEN
(SELECT MAX(id) FROM tab tp WHERE tp.id < t.id AND tp.fav_num = 3)
AND (SELECT MIN(id) FROM tab tn WHERE tn.id > t.id AND tn.fav_num = 3)
SELECT ID FROM tbl WHERE fav_num BETWEEN '1' AND '3';
請解釋它爲什麼可行。 –
http://sqlfiddle.com/#!9/2b6fb0/12
SELECT t1.*
FROM t1
INNER JOIN (SELECT
@d1:[email protected] d1,
@d2:[email protected] d2,
@d3:=fav_num d3,
@previd:[email protected] prevID,
@id:=id
FROM (
SELECT *
FROM t1
ORDER BY id) t
) filter
ON filter.d1 = 3
AND filter.d3 = 3
AND t1.id = filter.prevID
;
請試試這個：
SELECT a.id FROM test1 a WHERE
3=(SELECT fav_num FROM test1 WHERE id = (SELECT MAX(id) FROM test1 WHERE id <a.id)) AND
3=(SELECT fav_num FROM test1 WHERE id = (SELECT MIN(id) FROM test1 WHERE id >a.id)) ;
SELECT a.id FROM test1 a WHERE
EXISTS (SELECT 1 FROM test1 WHERE id = (SELECT MAX(id) FROM test1 WHERE id <a.id) AND fav_num=3) AND
EXISTS (SELECT 1 FROM test1 WHERE id = (SELECT MIN(id) FROM test1 WHERE id >a.id) AND fav_num=3) ;
我不知道有關perfornance。
你是否專門尋找返回ID = 2的數據，或者這是一個通用規則來獲取數據庫中所有條目的fav_num = 2？ – Hexana
ID是否始終連續（沒有間隙）？ – Strawberry