Cleaning invalid dates
The date_first_observed column in the parking_violation dataset represents the date when the parking violation was first observed by the individual recording the violation. Unfortunately, not all date_first_observed values were recorded properly. Some records contain a '0' value for this column. A '0' value cannot be interpreted as a DATE automatically as its meaning in this context is ambiguous. The column values require cleaning to enable conversion to a proper DATE column.
In this exercise, you will convert the date_first_observed value of records with a '0' date_first_observed value into NULL values using the NULLIF() function, so that the field can be represented as a proper date.
Deze oefening maakt deel uit van de cursus
Cleaning Data in PostgreSQL Databases
Praktische interactieve oefening
Probeer deze oefening eens door deze voorbeeldcode in te vullen.
SELECT
-- Replace '0' with NULL
___(___, ___) AS date_first_observed
FROM
parking_violation;