For most query executions we will use the stragtical method of sending in paramValues as part of the execution input payload. However when the user wants to use a function value as the parameter value, engine does not understand this i.e for date param the functions now(), today(). Engine Does not support this because those functions require a building of execution nodes inside the execution plan. To continue supporting this execution flow , we will add let statements for parameter values with function values so that they can be evaluated to constants in the execution plan.