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Functions for Manipulating Data in PostgreSQL

Here you can access the tables used in the course. To access the table, you will need to specify the dvdrentals schema in your queries (e.g., dvdrentals.film for the film table and dvdrentals.country for the country table).

Note: When using sample integrations such as those that contain course data, you have read-only access. You can run queries, but cannot make any changes such as adding, deleting, or modifying the data (e.g., creating tables, views, etc.).

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Add notes about the concepts you've learned and SQL cells with queries you want to keep.

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DataFrameas
movie_info
variable
-- Add your own queries here
SELECT *
FROM dvdrentals.film
LIMIT 10

Explore Datasets

Use the different tables to explore the data and practice your skills!

  • Select the title, release_year, and rating of films in the film table.
    • Add a description_shortened column which contains the first 50 characters of the description column, ending with "...".
    • Filter the film table for rows where the special_features column contains "Commentaries".
  • Select the customer_id, amount, and payment_date from the payment table.
    • Extract date information from the payment_date column, creating new columns for the day, month, quarter, and year of transaction.
    • Use the rental table to include a column containing the number of days rented (i.e., time between the rental_date and the return_date).
  • Update the title column so that titles with multiple words are reduced to the first word and the first letter of the second word followed by a period.
    • For example:
      • "BEACH HEARTBREAKERS" becomes "BEACH H."
      • "BEAST HUNCHBACK" becomes "BEAST H."
    • Reformat your shortened title to title case (e.g., "BEACH H." becomes "Beach H.").
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DataFrameas
df
variable
CONCAT(first_name, '', last_name) = first_name || '' || last_name
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DataFrameas
df1
variable
Kiedy potrzebujemy skórcić tekst do określonej liczby znaków (tutaj 50) ale nie chcemy mieć uciętego słowa. żeby znaleźć odpowiednią liczbę znaków dla funkcji LEFT odejmujemy od 50 pozycję, na kótrej znajduje się pierwsza spacja w odwróconym ciągu znaków. 

SELECT 
  UPPER(c.name) || ': ' || f.title AS film_category, 
  -- Truncate the description without cutting off a word
  LEFT(description, 50 - 
    -- Subtract the position of the first whitespace character
    POSITION(
      ' ' IN REVERSE(LEFT(description, 50))
    )
  ) 
FROM 
  film AS f 
  INNER JOIN film_category AS fc 
  	ON f.film_id = fc.film_id 
  INNER JOIN category AS c 
  	ON fc.category_id = c.category_id;