我对以下代码有疑问:MySqlConnectionconDatabase=newMySqlConnection(myConne);MySqlCommandcmdDataBase=newMySqlCommand("Select*fromsupplier_data,brandswherebrands.supplier_id=supplier_data.supplier_id",conDatabase);MySqlDataAdaptersda=newMySqlDataAdapter();sda.SelectCommand=cmdDataBase;System.Data.DataTabledb