2) The result of above calculation i need to use in different calculation . means output of this calculation will let us to determine the value of some parameters of other equation like below
where x1,y1,x2,y2 parameters are defined and whose value need to be picked based on value of x (being calculated from above scenario provided with sample data)
So, is the real data likely to be as perfect as your sample data or do you need something more robust? With the clean data using the lag window function will readily solve your problem. But if you could guarantee this clean of data I would probably have simply created two columns (and yes, I do know what normalization is) for timestamps - one of which can be null: the "second" one) and perform the query directly.