Implementing if/then with database search

Wow. I entered this question based on a title which led me to believe that this would be about implementing an IF...ELSE within an SQL script.
And then I get to the second line which contains a list of tags; consisting of 3 different programming languages and 2 different operating systems.

Quick Answers are meant for specific problems within a block of code. You do not have any code written yet... So this question really does not belong here.

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That said... The best thing for you to do is:
1. Make a flow chart of the business and functional requirements.
2. Choose a platform to implement the logic on.
3. Write code on a function by function basis

When you do have a problem with implementing a block of code, then you can post a question here containing both an explanation of what it is supposed to do, the code itself giving you the problem, and finally what is happening incorrectly or the error that is happening.

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Just from what you have posted; it looks like you are going to be building a client-server application, so you are going to need to build a couple of items:
1. A Web-Service which is going to do the majority of the work.
2. A database server to contain your data tables.
3. Apps for both Android and iOS devices

I would also recommend building a website to mimic the operations of the client apps. This will allow easier testing for you and can later be re-purposed for people who use desktop computers.

Also, a second website or app set for administration as needed.
If you needed to do this, then you are going to have to have Authentication/Authorization setup so that you can restrict access to it.