MYSQL：選擇更改的行，其中

Question

1 -

create table changes(snapdate date,value int, uid int); 
insert into changes values 
('2013-04-22', 0, 1), 
('2013-04-21', 1,1), 
('2013-04-20', 1,1), 
('2013-04-19', 1,1), 
('2013-04-19', 0,2), 
('2013-04-19', 1,1), 
('2013-04-18', 0,1), 
('2013-04-17', 0,1), 
('2013-04-17', 1,2), 
('2013-04-16', 1,1), 
('2013-04-16', 0 ,2); 

2 -

SELECT a.snapdate, a.value 
FROM ( 
    SELECT t1.*, COUNT(*) AS rank 
    FROM changes t1 
    LEFT JOIN changes t2 ON t1.snapdate >= t2.snapdate 
    GROUP BY t1.snapdate 
) AS a 
LEFT JOIN ( 
    SELECT t1.*, COUNT(*) AS rank 
    FROM changes t1 
    LEFT JOIN changes t2 ON t1.snapdate >= t2.snapdate 
    GROUP BY t1.snapdate 
) AS b ON a.rank = b.rank+1 AND a.value = b.value 
WHERE b.snapdate IS NULL 
ORDER BY a.snapdate DESC; 

工作正常，但如何選擇WHERE uid=2例如？ 我不能使用臨時表：

create temporary table changes_temp 
    as 
    select * 
    from changes 
    where uid = 2 

http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html

Answer 1

嘗試添加WHERE子句中的子查詢的

SELECT a.snapdate, a.value 
FROM ( 
    SELECT t1.*, COUNT(*) AS rank 
    FROM changes t1 
    LEFT JOIN changes t2 ON t1.snapdate >= t2.snapdate 
    WHERE t2.uid=t1.uid AND t2.uid=2 
    GROUP BY t1.snapdate 
) AS a 
LEFT JOIN ( 
    SELECT t1.*, COUNT(*) AS rank 
    FROM changes t1 
    LEFT JOIN changes t2 ON t1.snapdate >= t2.snapdate 
    WHERE t2.uid=t1.uid AND t2.uid=2 
    GROUP BY t1.snapdate 
) AS b ON a.rank = b.rank+1 AND a.value = b.value 
WHERE b.snapdate IS NULL 
ORDER BY a.snapdate DESC; 

創建SQLFiddle進行測試。 這就是你想要的嗎？你沒有解釋你的查詢的目標

Answer 2

添加where子句：

SELECT a.snapdate, a.value 
FROM ( 
    SELECT t1.*, COUNT(*) AS rank 
    FROM changes t1 
    LEFT JOIN changes t2 ON t1.snapdate >= t2.snapdate 
    WHERE t1.uid = 2 
    GROUP BY t1.snapdate 
) AS a 
LEFT JOIN ( 
    SELECT t1.*, COUNT(*) AS rank 
    FROM changes t1 
    LEFT JOIN changes t2 ON t1.snapdate >= t2.snapdate 
    WHERE t1.uid = 2 
    GROUP BY t1.snapdate 
) AS b ON a.rank = b.rank+1 AND a.value = b.value 
WHERE b.snapdate IS NULL 
ORDER BY a.snapdate DESC; 

sqlfiddle