CREATE TABLE table_203_27 (id NUMBER, "number" NUMBER, "serial no" NUMBER, "entered service" CLOB, "withdrawn" CLOB, "kilometres travelled" NUMBER)

which locomotive entered service first : 4107 or 4103 ?
SELECT "number" FROM table_203_27 WHERE "number" IN (4107, 4103) ORDER BY "entered service" LIMIT 1
SELECT "number" FROM "table_203_27" WHERE "number" IN (4107, 4103) ORDER BY "entered service" FETCH FIRST 1 ROWS ONLY