I guess your StudentAddress table is a link table between Address and Student tables, right?
If so, when you edit the link you better delete and insert "link" rows if they change, not update them.
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"The only true wisdom is in knowing you know nothing"
"O skol'ko nam otkrytiy chudnyh prevnosit microsofta duh!":-D
(So many miracle inventions provided by MS to us...)
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