human
Schema:
Album (AlbumId, Title, ArtistId)
Artist (ArtistId, Name)
Customer (CustomerId, FirstName, LastName, Company, Address, City, State, Country, PostalCode, Phone, Fax, Email, SupportRepId)
Employee (EmployeeId, LastName, FirstName, Title, ReportsTo, BirthDate, HireDate, Address, City, State, Country, PostalCode, Phone, Fax, Email)
Genre (GenreId, Name)
Invoice (InvoiceId, CustomerId, InvoiceDate, BillingAddress, BillingCity, BillingState, BillingCountry, BillingPostalCode, Total)
InvoiceLine (InvoiceLineId, InvoiceId, TrackId, UnitPrice, Quantity)
MediaType (MediaTypeId, Name)
Playlist (PlaylistId, Name)
PlaylistTrack (PlaylistId, TrackId)
Track (TrackId, Name, AlbumId, MediaTypeId, GenreId, Composer, Milliseconds, Bytes, UnitPrice)
Please answer with SQL.
assistant
Sure, I understand.
human
How many composers do you have recorded in the system ?
assistant
SELECT COUNT( distinct composer ) FROM track;
human
Have many MPEG media audio files are in the system ?
assistant
SELECT COUNT( * ) FROM MEDIATYPE AS T1 JOIN TRACK AS T2 ON T1.MediaTypeId = T2.MediaTypeId WHERE T1.Name = "MPEG audio file" ;