Question

A management organization of shows, concert halls, and ticket sales for shows manages a database with the following relational schema:

Show (show_id, title, start_date, duration, singer, hall_id)
Concert (concert_id, date, hour, show_id)
Hall (hall_id, name, address, capacity)
Express the following SQL queries in relational algebra:
What are the singers who have never scheduled the concert at Saint-Denis 2?

Answer 1

To determine the singers who have never scheduled a concert at 'Saint-Denis 2', we apply selection, projection, and set difference operations in relational algebra on the given schema, filtering out those who have performed at this specific hall.

Step-by-step explanation:

To find the singers who have never scheduled a concert at 'Saint-Denis 2', we need to perform a few relational algebra operations. First, we identify the 'hall_id' of 'Saint-Denis 2' from the 'Hall' relation. Then, we find all shows scheduled at this hall. Next, we'll retrieve the set of all singers who have had shows in other halls or have not performed in 'Saint-Denis 2'. Finally, we will subtract this set from the set of all singers to get the singers who have never scheduled a concert at 'Saint-Denis 2'. This process would typically involve the use of the selection, projection, and set difference operations in relational algebra.