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Using EXTRACT

You can use EXTRACT() and DATE_PART() to easily create new fields in your queries by extracting sub-fields from a source timestamp field.

Now suppose you want to produce a predictive model that will help forecast DVD rental activity by day of the week. You could use the EXTRACT() function with the dow field identifier in our query to create a new field called dayofweek as a sub-field of the rental_date column from the rental table.

You can COUNT() the number of records in the rental table for a given date range and aggregate by the newly created dayofweek column.

This exercise is part of the course

Functions for Manipulating Data in PostgreSQL

View Course

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

SELECT 
  -- Extract day of week from rental_date
  ___(___ ___ ___) AS dayofweek 
FROM rental 
LIMIT 100;
Edit and Run Code