TDDE: Transformations in DBT

[donaldsawyer]

Develop the transformation to select data from ontime_data, join it to carrier_code, and perform projection. New table is ontime_carrier.

Transformations:.

1. Join on carrier column
2. description renamed to carrier_desc
3. Calculate arrived_flag
   1. Y when not cancelled or diverted
   2. N when cancelled or diverted
   3. NULL when not cancelled or diverted, but arr_delay is NULL
4. Columns: year, month, day_of_month, carrier_code, carrier_desc, flight_number,origin, destination,arrived_flag

Acceptance Criteria:

1. Tests written in DBT via tests and/or data constraints in model for ontime_carrier
   1. Cancelled
   2. Diverted
   3. Not cancelled/diverted, but arr_delay is NULL. Feature reference
   4. JOIN on missing carrier should result in UNKNOWN for carrier_desc
   5. There should only be one row per unique flight (think: what happens when there are multiple rows?)
   6. only listed columns exist, and in order
2. Model for ontime_carrier written
3. Run on full dataset