CREATE TABLE table_64251 ("Class" CLOB, "Railway number ( s ) " CLOB, "Quantity" FLOAT, "Year ( s )  of manufacture" CLOB, "Axle arrangement  (  UIC  ) " CLOB)

what is the class when the quantity is 4?
SELECT "Class" FROM table_64251 WHERE "Quantity" = '4'
SELECT "Class" FROM "table_64251" WHERE "Quantity" = '4'