>>>I wonder how do you handle the RI in VFP. VFP have a mechanism for RI. However, when I test it, I feel it is very restricted. Does VFP have complete functions for accessing the RI rules in a defined database (*.dbc)?
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>>Yes, it has. Look at DBGetProp table properties.
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>DBGetProp does not seem to tell you the relationship among the tables. How can I find what is the relationship (master-detail) among the tables in a form, what are the link fields, what are the rules for deletion, changing key, etc. in run time?

IMHO, the appropriate answer here is that RI is not for run-time manipulations. Actually, it's stuff done during development, and defined once it can be documented and kept. However, if you want e.g. Delete/Create Trigger in run-time , you can do it (never tried, but believe it should be).