CREATE TABLE table_30017 ("Province" TEXT, "Provincial capital" TEXT, "Commandery" TEXT, "Commandery capital" TEXT, "No. of counties" FLOAT)

When nanhai is the commandery what is the commandery capital?
SELECT "Commandery capital" FROM table_30017 WHERE "Commandery" = 'Nanhai 南海'
SELECT "Commandery capital" FROM "table_30017" WHERE "Commandery" = 'Nanhai 南海'