Get height from reversing BMI calculation (oracle)-CodePudding

Seems that it should be simple enough to reverse engineer the bmi formula when you have the BMI and weight to get height -but perhaps not enough coffee today

(kg/power(m,2)) = BMI

but if I have

with T as (select 72.6 as kg, 28.35 as BMI_supplied  from dual)

what is the reverse to get the height (should be 1.6m)

Thanks in advance for your time.

CodePudding user response：

Rearrange the equation:

Step	Equation	Action
1.	BMI = weight / height²
2.	BMI × height² = weight	Multiply both sides by height²
3.	height² = weight / BMI	Divide both sides by BMI
4.	height = SQRT(weight / BMI)	Take the square root of both sides

So:

WITH T (weight_kg, BMI_supplied) AS (
  SELECT 72.6, 28.35 FROM DUAL
)
SELECT weight_kg,
       SQRT(weight_kg / BMI_supplied) AS height_m,
       BMI_supplied
FROM   T;

Which outputs:

WEIGHT_KG HEIGHT_M BMI_SUPPLIED

72.6 1.60026452839727746261804822638120931361 28.35

WEIGHT_KG	HEIGHT_M	BMI_SUPPLIED
72.6	1.60026452839727746261804822638120931361	28.35

db<>fiddle here