Appunti BD1

Made by billy, davide, vincenzo.

The correctness is not guaranteed. Use at your own risk.

Sections

• Introduction of notation: basic symbols, schemes, tuples, keys, legality.
• Relational algebra query patterns: existential vs universal, at-least-k, min/max by self-join.
• Armstrong's axioms: axioms and derived rules with quick examples.
• Finding the (minimal) keys: heuristic and closure-based procedure.
• Finding a minimal cover of \(F\): step-by-step recipe plus example.
• Checking if \(R\) satisfies 3NF: conditions and worked check.
• Check for a lossless join (JSP): chase and key-containment tests with example.
• Find a 3NF decomposition (Bernstein): synthesis algorithm.
• Check if a decomposition preserves \(F\): projections, closure, and examples.
• Compute \(X_G^+\) from \(F\): procedure for projected closure.
• Minimal cover walkthrough: worked example with Mermaid graphs.
• Physical organization: clustered vs non-clustered, indexes, pros and cons.
• Proofs: various proofs of theorems and properties.
• Quiz in Italian: practice questions with answers and references.