查詢和通過施加一個特定的濾波器

Question

我已經含有特定項目的ID和整個的一定時間內其相應的生產成本下表（只樣品）（在這種情況下被省略）

| id | cost| 
|------|-----| 
| 1667 | 20 | 
| 2000 | 25 | 
| 2000 | 30 | 
| 1667 | 35 | 
| 3244 | 500 | 
| 3244 | 0 | 
| 3244 | 25 | 
| 3244 | 26 | 
| 9999 | 56 | 
| 3814 | 526 | 
| 9999 | 699 | 
| 3814 | 13 | 

分組數據

我想提取每個特定ID的最大值，到目前爲止我已經成功。輸出看起來像這樣：

| id | cost | 
|------|-------| 
| 2000 | 30 | 
| 1667 | 35 | 
| 3244 | 500 | 
| 3814 | 526 | 
| 9999 | 699 | 

我使用的代碼是：

SELECT * 
FROM t1 WHERE (id,cost) IN 
(SELECT id, max(cost) 
FROM t1 
GROUP BY id 
) 

不過，我想獲得最大價值，因爲有時成本爲0或進入之前應用額外的過濾器數字太高。

• 首先，我想排除價格= 0的所有ID。
• 其次，我想排除高於特定ID的2x3rd四分位數的所有價格。

例如，如果我們把ID = 3244，過程是這樣的：

| id | cost |  | id | cost |  | id | cost | 
|------|-------|  |------|-------|  |------|-------| 
| 3244 | 500|  | 3244 | 500|  |  |  | 
| 3244 |  0|  |  |  |  |  |  | 
| 3244 |  25|  | 3244 |  25|  | 3244 |  25| 
| 3244 |  26|  | 3244 |  26|  | 3244 |  26| 

我會得到ID = 3244將是26號，我想重複這個過程每個ID。

Answer 1

使用這種definition

For a set of data, a number for which 75% of the data is less than that number. The third quartile is the same as the median of the part of the data which is greater than the median. Same as 75th percentile.

SqlFiddle Demo

SELECT item.id, MAX(cost) cost 
FROM item 
JOIN (
     SELECT item.id, avg(cost) thirdQ 
     FROM item 
     JOIN (
       SELECT id, avg(cost) mean_cost 
       FROM item 
       WHERE cost <> 0 
       GROUP BY id 
      ) T1 
     ON item.id = T1.id 
     WHERE cost > mean_cost and cost <> 0 
     GROUP BY item.id 
    ) T2 
    ON item.id = T2.id 
WHERE cost < T2.thirdQ 
GROUP BY item.id 

OUPUT

| id | cost | 
|------|------| 
| 1667 | 20 | 
| 2000 | 25 | 
| 3244 | 26 | 
| 3814 | 13 | 
| 9999 | 56 |