CREATE TABLE playlisttrack (playlistid DECIMAL, trackid DECIMAL)
CREATE TABLE artist (artistid DECIMAL, name TEXT)
CREATE TABLE invoiceline (invoicelineid DECIMAL, invoiceid DECIMAL, trackid DECIMAL, unitprice DECIMAL, quantity DECIMAL)
CREATE TABLE invoice (invoiceid DECIMAL, customerid DECIMAL, invoicedate TIME, billingaddress TEXT, billingcity TEXT, billingstate TEXT, billingcountry TEXT, billingpostalcode TEXT, total DECIMAL)
CREATE TABLE mediatype (mediatypeid DECIMAL, name TEXT)
CREATE TABLE genre (genreid DECIMAL, name TEXT)
CREATE TABLE track (trackid DECIMAL, name TEXT, albumid DECIMAL, mediatypeid DECIMAL, genreid DECIMAL, composer TEXT, milliseconds DECIMAL, bytes DECIMAL, unitprice DECIMAL)
CREATE TABLE customer (customerid DECIMAL, firstname TEXT, lastname TEXT, company TEXT, address TEXT, city TEXT, state TEXT, country TEXT, postalcode TEXT, phone TEXT, fax TEXT, email TEXT, supportrepid DECIMAL)
CREATE TABLE album (albumid DECIMAL, title TEXT, artistid DECIMAL)
CREATE TABLE playlist (playlistid DECIMAL, name TEXT)
CREATE TABLE employee (employeeid DECIMAL, lastname TEXT, firstname TEXT, title TEXT, reportsto DECIMAL, birthdate TIME, hiredate TIME, address TEXT, city TEXT, state TEXT, country TEXT, postalcode TEXT, phone TEXT, fax TEXT, email TEXT)

What are the different first names for customers from Brazil who have also had an invoice?
SELECT DISTINCT T1.firstname FROM customer AS T1 JOIN invoice AS T2 ON T1.customerid = T2.customerid WHERE T1.country = "Brazil"
SELECT DISTINCT "T1"."firstname" FROM "customer" AS "T1" JOIN "invoice" AS "T2" ON "T1"."customerid" = "T2"."customerid" WHERE "Brazil" = "T1"."country"