mysql - 如何在 MySQL 中进行插值

Question

我在 MySQL 数据库中有两个表，我需要一个插值函数，但我不确定如何处理这个问题。这两个表看起来像:

表 1 看起来像……

+----------+-------+
| speed    | Calc  |
+----------+-------+
|    3     |       |
|    4     |       |
|    5     |       |
|    6     |       |
|    7     |       |
|    8     |       |
|    9     |       |
|    10    |       |
|    11    |       |
|    12    |       |
|    13    |       |
|    14    |       |
|    15    |       |
+----------+-------+

表 2 如下所示:

+----------+---------+
| speed    |binspeed |
+----------+---------+
|    3     | 29.1835 |
|    5     | 16.7992 |
|    10    | 10.5918 |
|    15    | 8.4319  |
+----------+---------+

我几乎需要检查表 1 中的每个速度。如果速度与表 2 中的 avgBinSpeed 匹配，那么我设置 Calc = binspeed。如果速度在值之间，我需要使用一个函数而不是使用下一个较低和较高的值，例如 calc = lower binspeed + ((table1.speed- lower avgBinSpeed value)/(next avgBinSpeed value))*( next binspeed – lower binspeed) 作为速度 3 和 4 的示例。

If (Table1.speed = 3)
(update table1 T
Inner join table2 X
On t.speed = x.speed
Set Oregon = binspeed);

If (Table1.speed = 4)
(update table1 T
Inner join table2 X
On t.speed = x.spedd
Set Oregon = (29.1835+((4-3)/(5-3))*( 16.7921-29.1835));

这是我不知道该怎么做。由于 4 在 avgBinSpeed 3 和 5 之间，我需要使用 binspeed 3 (29.1835) + ((speed (4) – speed (3))/( avgBinSpeed (5) - avgBinSpeed (3))) * (binspeed of 5 (16.7992) – binspeed of 3 (29.1835)。我该如何解决这个问题才能得到类似下表的结果？

+----------+-------+
| speed    | Calc  |
+----------+-------+
|    3     | 29.18352307 |
|    4     | 22.98782107 |
|    5     | 16.79211907 |
|    6     | 15.55207188 |
|    7     | 14.31202469 |
|    8     |       |
|    9     |       |
|    10    |       |
|    11    |       |
|    12    |       |
|    13    |       |
|    14    |       |
|    15    |       |
+----------+-------+

Answer 1

此查询将构建数据，然后为您进行计算。试试看:)

SET @a := null;
SET @d := null;
SET @bin := null;
set @e := null;

UPDATE table1 temp,
(   SELECT 
        speed, 
        IF(
            base_col IS NULL, 
            (old_binspeed +((speed - old_speed)/(new_speed - old_speed) ) * (new_binspeed - old_binspeed)), 
            base_col
        ) AS update_col
    FROM
    (   SELECT *, 
        IF(binspeed IS NULL, test, binspeed) AS new_binspeed,
        IF(binspeed IS NULL, @BIN, @BIN := binspeed) AS old_binspeed,
        IF(test1 IS NULL, @D, @D := test1) AS new_speed,
        IF(test1 IS NULL, @E, @E := speed) AS old_speed,
        @A := binspeed AS base_col
        FROM
        (    SELECT t1.speed, t2.binspeed,
                (SELECT binspeed FROM table2 WHERE speed > t1.speed ORDER BY speed LIMIT 1) test,
                (SELECT speed FROM table2 WHERE speed > t2.speed ORDER BY speed LIMIT 1) test1
            FROM table1 t1
            LEFT JOIN table2 t2 ON t2.speed = t1.speed
        )t4
    ORDER BY speed
    ) tt
)temp1
SET temp.Calc = temp1.update_col 
    WHERE temp.speed = temp1.speed
;

这是一个DEMO