查找表中作爲列兩個領域之間的區別

Question

我有以下

SELECT 
ttstudent.ttstudentid, 
ttstudent.studentid, 
ttstudent.subjectid, 
ttstudent.classnumber, 
ttstudent.classid, 
concat(student.fn, " ", student.sn) AS Student, 
SUM(If(ondemand.cycle="Feb7" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr7 Feb`, 
SUM(If(ondemand.cycle="Jul7" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr7 July`, 
SUM(If(ondemand.cycle="Feb8" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr8 Feb`, 
SUM(If(ondemand.cycle="Jul8" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr8 July`, 
SUM(If(ondemand.cycle="Feb9" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr9 Feb`, 
SUM(If(ondemand.cycle="Jul9" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr9 July`, 
SUM(If(ondemand.cycle="Feb10" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr10 Feb`, 
SUM(If(ondemand.cycle="Jul10" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr10 Aug`, 
ondemand.Student_ID 
FROM ttstudent 
INNER JOIN student ON ttstudent.studentid = student.code 
INNER JOIN ondemand ON ttstudent.studentid = ondemand.Student_ID 
GROUP BY ondemand.Student_ID 

這產生了25人左右的柱狀清單與最後一列找到最後2之差計算字段下面的SQL表中的值。得分是時間戳。

CODE |Year7Feb|Year7Jul|Year8Feb|Year8Jul|Year9Feb|Year9Jul| Year10Feb| Growth 
abe1 | 2.3 | 2.9 |  |  |  |  |   | .6 
bas1 |  |  | 3.5 | 3.7 |  |  |   | .2 
cod |  |  |  |  |  | 4.5 | 5.2 | .7 

我想這樣做是另一列添加這將需要從每個用戶（無論列它是）最後兩個得分並找到差異。我會稱這一列增長。

我正在努力使用以外的最大值。有任何想法嗎？

Answer 1

這應該做的伎倆：

計算列growth用下面的查詢

SELECT si,ty,la.uid laid,pr.uid prid,(la.score-pr.score) growth FROM ( 
SELECT si,ty,max(test_date) cyprev, cylast FROM ondemand INNER JOIN (
    SELECT Student_ID si,type ty,max(test_date) cylast FROM ondemand 
     GROUP BY Student_ID,type 
) od ON si=Student_ID AND ty=type AND cylast>test_date 
GROUP BY si,ty, cylast 
) getlast2 
INNER JOIN ondemand la ON la.Student_Id=si AND la.type=ty AND la.test_date=cylast 
INNER JOIN ondemand pr ON pr.Student_Id=si AND pr.type=ty AND pr.test_date=cyprev 

，然後LEFT JOIN到您的整個查詢（略簡化此版本）：

SET @subj:="Numeracy"; 
SELECT Student_id, 
SUM(If(ondemand.cycle="Feb7" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr7 Feb`, 
SUM(If(ondemand.cycle="Jul7" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr7 July`, 
SUM(If(ondemand.cycle="Feb8" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr8 Feb`, 
SUM(If(ondemand.cycle="Jul8" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr8 July`, 
SUM(If(ondemand.cycle="Feb9" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr9 Feb`, 
SUM(If(ondemand.cycle="Jul9" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr9 July`, 
SUM(If(ondemand.cycle="Feb10" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr10 Feb`, 
SUM(If(ondemand.cycle="Jul10" and ondemand.type=@subj, ondemand.Score, NULL)) AS `Yr10 Aug`, 
growth 
FROM ondemand LEFT JOIN (
SELECT si,ty,la.uid laid,pr.uid prid,(la.score-pr.score) growth FROM ( 
    SELECT si,ty,max(test_date) cyprev, cylast FROM ondemand INNER JOIN (
    SELECT Student_ID si,type ty,max(test_date) cylast FROM ondemand 
      GROUP BY Student_ID,type 
) od ON si=Student_ID AND ty=type AND cylast>test_date 
    GROUP BY si,ty, cylast 
) getlast2 
INNER JOIN ondemand la ON la.Student_Id=si AND la.type=ty AND la.test_date=cylast 
INNER JOIN ondemand pr ON pr.Student_Id=si AND pr.type=ty AND pr.test_date=cyprev 
) gt ON si=Student_id AND ty=@subj 
GROUP BY Student_id; 

我忽略了JOIN s到表student和ttstudent及其列

ttstudent.ttstudentid, 
ttstudent.studentid, 
ttstudent.subjectid, 
ttstudent.classnumber, 
ttstudent.classid, 
concat(student.fn, " ", student.sn) AS Student 

編輯：

剛纔用你test_date列的變化。子查詢在MySQL中進行了測試，我希望它也可以在您的數據庫中使用。

EDIT2：

我慢慢看到你從哪裏來。它變得越來越複雜（剛填充有關type="Numeracy"的XTRA條件......也許還有畢竟是一個簡單的解決方案？

不管怎麼說，這是一個SQLfiddle證明整個事情（在這裏修改後的版本：sqlfiddle2）

第三次和最後編輯：

你可能需要的是對SQLfiddle3東西線（ - >只一個 SELECT命令沒有前面的SET聲明）。你完整的命令應該再是這個樣子：

SELECT 
ttstudent.ttstudentid, 
ttstudent.studentid, 
ttstudent.subjectid, 
ttstudent.classnumber, 
ttstudent.classid, 
concat(student.fn, " ", student.sn) AS Student, 
SUM(If(ondemand.cycle="Feb7" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr7 Feb`, 
SUM(If(ondemand.cycle="Jul7" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr7 July`, 
SUM(If(ondemand.cycle="Feb8" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr8 Feb`, 
SUM(If(ondemand.cycle="Jul8" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr8 July`, 
SUM(If(ondemand.cycle="Feb9" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr9 Feb`, 
SUM(If(ondemand.cycle="Jul9" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr9 July`, 
SUM(If(ondemand.cycle="Feb10" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr10 Feb`, 
SUM(If(ondemand.cycle="Jul10" and ondemand.type="Numeracy", ondemand.Score, NULL)) AS `Yr10 Aug`, 
ondemand.Student_ID, 
getdif.growth 
FROM ttstudent 
INNER JOIN student ON ttstudent.studentid = student.code 
INNER JOIN ondemand ON ttstudent.studentid = ondemand.Student_ID 
LEFT JOIN (
SELECT si,ty,la.uid laid,pr.uid prid,(la.score-pr.score) growth FROM ( 
    SELECT si,ty,max(test_date) cyprev, cylast FROM ondemand INNER JOIN (
    SELECT Student_ID si,type ty,max(test_date) cylast FROM ondemand 
      GROUP BY Student_ID,type 
) od ON si=Student_ID AND ty=type AND cylast>test_date 
    GROUP BY si,ty, cylast 
) getlast2 
INNER JOIN ondemand la ON la.Student_ID=si AND la.type=ty AND la.test_date=cylast 
INNER JOIN ondemand pr ON pr.Student_ID=si AND pr.type=ty AND pr.test_date=cyprev 
) getdif ON si=ondemand.Student_ID AND ty=ondemand.type 
WHERE ondemand.type='Numeracy' 
GROUP BY ondemand.Student_ID 

我以前的版本中體現我的個人避免任何冗餘的偏愛，也是我的志向參數化的東西儘可能。但是我可能走得太遠了;-)。