Testing if a value is NULL
eSymphony is interested in knowing the number of tracks that are not in a playlist and cost $1.99. Since they know songs in a playlist are bought more often, they want to get an idea of the potential revenue they are missing out on.
To answer this question you will need to join the data and look at the NULL values added where the join condition is not met.
Diese Übung ist Teil des Kurses
Introduction to Oracle SQL
Anleitung zur Übung
- Select the total count of resulting rows.
- Perform the appropriate join between the
TrackandPlaylistTracktables. - Filter on tracks that are not in a playlist and cost $1.99.
Interaktive Übung
Versuche dich an dieser Übung, indem du diesen Beispielcode vervollständigst.
-- Count the number of rows in the result
SELECT ___(*) AS SongCount
-- Perform the appropriate join
FROM ___
ON t.___ = p.___
-- Filter on tracks not in a playlist and cost $1.99
WHERE p.___ ___ ___ AND t.UnitPrice = ___