Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_30017 ( "Province" text, "Provincial capital" text, "Commandery" text, "Commandery capital" text, "No. of counties" real )

### Question ###
When nanhai is the commandery what is the commandery capital?

### Accurate SQL ###

SELECT "Commandery capital" FROM table_30017 WHERE "Commandery" = 'Nanhai 南海'