1c_query.txt

pi Track.Name, Track.TrackId((Track ⨝ Track.TrackId = InvoiceParts.TrackId InvoiceParts) ⨝ Track.GenreId = Genre.GenreId (sigma Genre.Name ='Rock'(Genre)))

#   Titel, d. h. Tracks, des Genres „Rock“, die auch tatsächlich gekauft wurden angeben!!

# selection operation (σ) to filter rows from the "Genre" relation. 
# It selects rows where the "Name" column in the "Genre" relation is equal to 'Rock'.

# join operation (⨝) between the result obtained from Step 1 and the "Track" relation.
# The condition for the join is that the "GenreId" in the "Track" relation must be equal to the "GenreId" in the filtered "Genre" relation.

# join operation is performed between the result obtained from Step 2 and the "InvoiceParts" relation.
# The condition for this join is that the "TrackId" in the "Track" relation must be equal to the "TrackId" in the "InvoiceParts" relation.

# projection operation (π) is applied to the result obtained from Step 3.
# It selects specific columns, namely "Name" and "TrackId," from the joined result.