CREATE TABLE table_64261 ("Class" CLOB, "Railway number ( s ) " CLOB, "Quantity" CLOB, "Year ( s )  of manufacture" CLOB, "Type" CLOB)

What is the class with 1 quantity?
SELECT "Class" FROM table_64261 WHERE "Quantity" = '1'
SELECT "Class" FROM "table_64261" WHERE "Quantity" = '1'