It does not work like this here.
Here is what is expected of enquirers:
1. TRY first what you want to do! You may find that it's not that hard.
2. Formulate what was done by you that looks like an issue/not working.
Try them and tell if you face issues.
Members will be more than happy to help like this.
Getting/Expecting code is not a good way - try to gather the requirements first, decide on features. Look at few existing inventory system. Develop one. Do post questions if you face any issue while implementing it. Start looking from Google
] to see what all are shared on the topic.