CREATE TABLE "table_of_locomotives" (
  "class" text,
  "gnri_no" real,
  "name" text,
  "bp_serial_no" real,
  "rebuilt" real,
  "1958" text,
  "withdrawn" real
);

Question: What is the smallest withdrawn value with a GNRI greater than 172, name of Croagh Patrick and was rebuilt before 1939?
SQL: SELECT MIN("withdrawn") FROM "table_of_locomotives" WHERE "gnri_no">172 AND "name"='croagh patrick' AND "rebuilt"<1939;