To offer free shipping (or no shipping cost by your meaning) site-wide, simply enable free shipping of your carrier under Back office / Shipping / Carriers.
Good luck!
我想知道,你从哪里了解到“mysql批量导入产品的表是两张表”
但,批量导入产品可以直接在BO里操作:Back Office / ADVANCED PARAMETERS / CSV IMPORT / What kind of entity would you like to import? (选择Products);右侧的available fields可以了解到mysql里产品table所需要的parameters;右下则是sample csv文件。
p.s. Back up before mess up.