Table: south_korean_surnames
Columns: hangul
hanja
revised
mccune_reischauer
2000_n_south_korea_population

Question: What is the Hanja for McCune-Reischauer of chŏn?
SQL: SELECT "hanja" FROM south_korean_surnames WHERE "mccune_reischauer" = 'chŏn'

Question: What is the Hangul when the Hanja is 西, 徐?
SQL: SELECT "hangul" FROM south_korean_surnames WHERE "hanja" = '西, 徐'