old_contents: #!bin/env python
  
  import asyncpg
  
  class PGDB:
      def __init__(self, db_conn):
          self.db_conn = db_conn
  
      async def fetch_user_info(self, member_id: int, column: str):
          query = f'''SELECT {column} FROM user_info WHERE member_id = {member_id};'''
          return await self.db_conn.fetchval(query)
  
      async def insert_user_info(self, member_id: int, column: str, col_value):
          execute = (
              f'''INSERT INTO user_info (member_id, $1) VALUES ($2, $3)
                      ON CONFLICT member_id DO UPDATE SET $1 = $3;''')
          await self.db_conn.execute(execute, (column, member_id, col_value))
  
new_contents: #!bin/env python
  
  import asyncpg
  
  class PGDB:
      def __init__(self, db_conn):
          self.db_conn = db_conn
  
      async def fetch_user_info(self, member_id: int, column: str):
          query = f'''SELECT {column} FROM user_info WHERE member_id = {member_id};'''
          return await self.db_conn.fetchval(query)
  
      async def insert_user_info(self, member_id: int, column: str, col_value):
          execute = (
              f'''INSERT INTO user_info (member_id, {column}) VALUES ($1, $2)
                      ON CONFLICT member_id DO UPDATE SET {column} = $2;''')
          await self.db_conn.execute(execute, member_id, col_value)
  
subject: fix parameterization