>Where should I write business rules and data validation if I want to apply some client-server and n-tier concepts?
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>Should I use stored procedures?, Table´s field and record validation rules?
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>I don´t need to build a robust 3 tier app, but I want to begin separating data management and UI, so I would like to know good practices wich allow future scalability.
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>Let´s say: if the user must provide at least two fields (code + name) to be allowed to save a record, where do I put this validation?
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>Users have been using programs where they have buttons to navigate through the records (go next, prior, first, last), and perform incremental search, and even determine the sort order. How can I provide this environment using CS and n-tier techniques?
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>TIA.
On the record navigation, you may still use a local cursor to bring in a sub-set of data at a time, say by allowing the user to specify limited filter criteria. For example, on a customer's table, allow the user to select a letter of the alphabet and then have all customers that start with that letter downloaded to your local cursor for top-bottom, next-previous type of navigation.
I myself would steer away from this kind of Client/Server UI and only do it if the user says he must have it.
Just my 2 cents.