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Exercise

Filtering your CASE statement

Let's generate a list of matches won by Italy's Bologna team! There are quite a few additional teams in the two tables, so a key part of generating a usable query will be using your CASE statement as a filter in the WHERE clause.

CASE statements allow you to categorize data that you're interested in -- and exclude data you're not interested in. In order to do this, you can use a CASE statement as a filter in the WHERE statement to remove output you don't want to see.

Here is how you might set that up:

SELECT *
FROM table
WHERE 
    CASE WHEN a > 5 THEN 'Keep'
         WHEN a <= 5 THEN 'Exclude' END = 'Keep';

In essence, you can use the CASE statement as a filtering column like any other column in your database. The only difference is that you don't alias the statement in WHERE.

Instructions

100 XP
  • Use the CASE statement in the WHERE clause to filter where hometeam_id is 9857 and home goals exceed away goals.
  • Use the CASE statement in the WHERE clause to filter where awayteam_id is 9857 and away goals exceed home goals.
  • End the CASE statement by excluding games that Bologna did not win.