python mysqldb打印表a中不在表b中的行

我有两张桌子, sales_olap 和 resellers

我需要打印出转售商的来源 销售业务 不存在于 转售商 桌子

例如:

result = cursor.execute("SELECT SO.reseller_name FROM sales_olap AS SO WHERE 
SO.reseller_name!=(SELECT reseller FROM resellers)")
for row in result:
    print row

但我犯了个错误: 1242, Subquery returns more than 1 row

我怎样才能让它只打印经销商的名字 销售业务 它们不存在的表 转售商 桌子?

如果我试着做:

    result = cursor.execute("SELECT reseller_name FROM sales_olap WHERE reseller_name NOT IN(SELECT reseller FROM resellers)")
    for row in result:
        print row['reseller_name']

然后我得到错误: TypeError: 'long' object is not iterable