如何为单位转换建立表格模型？ [英] How do you model a table for unit conversion?

问题描述

我想要创建一个各种单位的数据库模型及其彼此之间的关系。例如，36英寸= 3英尺= 1码= 0.9144米等。该表还将存储盎司，磅，kg，克，厘米的杯子和各种测量。

I'm looking to create a db model of various units and their relation to each other. For instance, 36 inches = 3 feet = 1 yard = .9144 meters etc. This table would also store cups in ounces, pounds, kg, grams, cm and all sorts of measurements.

如何做到这一点？我在想这样的事情：

How do you do this? I was thinking about something like this:

Amount | Units | ConversionFactor | ConversionUnits
1      | foot  | 12               | inches
1      | yard  | 36               | inches

但是坦率地说，这似乎是一个可怕的想法。试图弄清楚在一个院子里有多少英尺会非常复杂，我不认为我可以存储所有我需要的转换。

But frankly, this seems like a terrible idea. Trying to figure out how many feet in a yard would be very convoluted, and I don't think I could ever store all the conversions I need.

还有什么其他想法？我知道这是一个解决的问题。感谢！

What other ideas are there? I know this is a solved problem. Thanks!

推荐答案

存储转换为SI单位，而不是其他非公制单位。然后你可以在单位之间转换，而不需要知道显式转换。

Store conversions to SI units, not to other non-metric units. Then you can convert between units in without needing to know the explicit conversion.

Unit         | Class      | Base Unit Multiplier
------------------------------------------------------
foot         | length     | 0.304800610
yard         | length     | 0.914401830
square foot  | area       | 0.092903040
...

所以14码的码是：

14 feet * 0.304800610 = 4.26720854 meters
4.26720854 meters * 0.914401830⁻¹ = 4.66666667 yards

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