SQL alternative to using while loop to create calculated measure - sql

Question

I am creating a field by performing some calculations.
Then in the next iteration I use that result to compute a new value. Currently doing this with a WHILE loop. Any other way?
I have tried LAG and Partition and even a recursive CTE but could not achieve the same outcome:
DECLARE #Period INT = 2;
DECLARE #MaxPeriod INT;
SELECT #MaxPeriod = Periods FROM dbo.Engine (NOLOCK);
WHILE (#Period <= #MaxPeriod)
BEGIN
WITH CTE AS (
SELECT
A.ProjectId, A.TypeId, A.Trial, A.Period,
((B.ValueA * (COALESCE(B.FactorCalculated, 0) + 1)) +
(A.ValueA * 0)) / A.ValueA AS FactorCalculated
FROM dbo.PenetrationResults A (NOLOCK)
INNER JOIN dbo.PenetrationResults B (NOLOCK)
ON A.ProjectId = B.ProjectId
AND A.TypeId = B.TypeId
AND A.Trial = B.Trial
AND (A.Period - 1) = B.Period
WHERE A.[Period] = #Period
AND A.ProjectId = #ProjectId
)
UPDATE [target]
SET FactorCalculated = CTE.FactorCalculated
FROM dbo.PenetrationResults AS [target] --(TABLOCK)
INNER JOIN CTE
ON [target].[ProjectId] = CTE.ProjectId AND [target].[TypeId] = CTE.TypeId
AND [target].[Trial] = CTE.Trial
AND [target].[Period] = CTE.Period
SET #Period = #Period + 1
END ;

Answer 1

Well I found a way to make this work using the CTE recursive abilities finally, improved performance 4 x
WITH ncte AS (
-- number the rows sequentially without gaps
SELECT
ProjectId,
TypeId,
Trial,
[Period],
FactorWifiCumulative--,
--FactorConnectedCalc
FROM dbo.PenetrationResults (NOLOCK)
WHERE ProjectId = #ProjectId
), rcte AS (
-- find first row in each group
SELECT *, CAST(0 AS DECIMAL(21,14)) AS Calc
FROM ncte AS base
WHERE Period = 1
UNION ALL
-- find next row for each group from prev rows
SELECT curr.*,
CAST(
(
(
prev.FactorWifiCumulative
*
(
COALESCE(prev.Calc,0)
+ 1
)
)
+
(
curr.FactorWifiCumulative*0
)
)
/
curr.FactorWifiCumulative AS DECIMAL(21,14))
AS Calc
--CAST(prev.Calc * (1 + curr.FactorWifiCumulative / 100) AS DECIMAL(21, 14))
FROM ncte AS curr
INNER JOIN rcte AS prev
ON curr.Period = prev.Period + 1
AND curr.TypeId = prev.TypeId
AND curr.Trial = prev.Trial
)
UPDATE [target]
SET [FactorConnectedCalc] = [Calc]
FROM dbo.PenetrationResults AS [target] (NOLOCK)
INNER JOIN rcte
ON [target].[ProjectId] = rcte.ProjectId
AND [target].[TypeId] = rcte.TypeId
AND [target].[Trial] = rcte.Trial
AND [target].[Period] = rcte.Period
OPTION(MAXRECURSION 0);