Introduction
Side-effects in functions
Invoking functions
Instruction
Good job! In a similar way, you can assign a function result to a variable.
Take a look at the function below, which finds the ID of the most common topic and highlights all opening posts in this topic:
CREATE FUNCTION highlight_most_frequent_topic_posts() RETURNS void AS $$ DECLARE topic_id integer; BEGIN topic_id := get_most_frequent_topic(); UPDATE post SET content = '*** ' + content WHERE topic_id = topic_id AND parent_id IS NULL; END; $$ LANGUAGE plpgsql;
Exercise
Write a new function named downvote() that takes one input parameter post_id of type integer and returns void.
The function should add 1 to the thumbs_down for the post with ID equal to post_id. If the new score (counted as thumbs_up - thumbs_down) is below -10, then the function should lock post author's account (using the function lock_post_author(post_id)).
Finally, the function should raise a notice saying:
User {user_id} has been locked because of downvotes in post {post_id}Stuck? Here's a hint!
A refresher: You may use the following syntax to include variables in the notice:
RAISE NOTICE 'Variable a = %, variable b = %', a, b;
