I saw one module folders and files in magento connect. in that only **etc, Helper, & Module** folder is present.

but there is no **sql** folder. but still that module created a text box in backend , so  that we can enter the zip codes in textfield and its going to be save in database.

so what is the reason behind that table. 

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/VL1AZ.png