Added the second dispatch

src/preprocessing.jl

@@ -51,4 +51,31 @@ function period_prior_to_index(cohort_id::Vector, conn; date_prior=Day(100), tab
  return df
 end
 
+"""
+TODO: Add Doc-Strings.
+"""
+function period_prior_to_index(
+ person_ids::Vector, 
+ start_date_on_person::Function, 
+ conn; 
+ date_prior=Day(100)
+ )
+
+ tables = GenerateTables(conn, inplace = false, exported=true)
+
+ sql = start_date_on_person(person_ids, tables)
+
+ df = DBInterface.execute(conn, String(sql)) |> DataFrame
+
+ # Check if the DataFrame is not empty
+ # TODO: Is it really necessary to add this check ??
+ if nrow(df) > 0
+ # Convert the cohort_start_date to DateTime and subtract the date_prior
+ df.cohort_start_date = DateTime.(df.cohort_start_date) .- date_prior
+ end
+
+ return df
+end
+
+
 export Dummy, period_prior_to_index