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Exercises

Solution 2:. Exercises. Reserves. Sailors. Boats. Solution 1: . Basic operations: Selection ( σ ) gives a subset of rows. Projection ( π ) Deletes unwanted cols. Cross-product (  ) combine two relations. Set-difference ( — ) Tuples in reln. 1,

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Exercises

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  1. Solution 2: Exercises Reserves Sailors Boats • Solution 1: Basic operations: Selection ( σ ) gives a subset of rows. Projection ( π ) Deletes unwanted cols. Cross-product(  ) combine two relations. Set-difference ( — ) Tuples in reln. 1, but not in reln. 2. Union(  ) Tuples in reln. 1 and in reln. 2. Additional operations: Intersection () – Tuples in both relns. Join ( ) – like  but only keep tuples where common fields equal Division ( / ) – tuples from reln 1 with matches in reln 2 Renaming ( ρ) – Rename columns Find names of sailors who’ve reserved boat #103

  2. A more efficient solution: Exercises Reserves Sailors Boats Basic operations: Selection ( σ ) gives a subset of rows. Projection ( π ) Deletes unwanted cols. Cross-product(  ) combine two relations. Set-difference ( — ) Tuples in reln. 1, but not in reln. 2. Union(  ) Tuples in reln. 1 and in reln. 2. Additional operations: Intersection () – Tuples in both relns. Join ( ) – like  but only keep tuples where common fields equal Division ( / ) – tuples from reln 1 with matches in reln 2 Renaming ( ρ) – Rename columns Find names of sailors who’ve reserved a red boat

  3. Exercises Reserves Sailors Boats Basic operations: Selection ( σ ) gives a subset of rows. Projection ( π ) Deletes unwanted cols. Cross-product(  ) combine two relations. Set-difference ( — ) Tuples in reln. 1, but not in reln. 2. Union(  ) Tuples in reln. 1 and in reln. 2. Additional operations: Intersection () – Tuples in both relns. Join ( ) – like  but only keep tuples where common fields equal Division ( / ) – tuples from reln 1 with matches in reln 2 Renaming ( ρ) – Rename columns Find sailors who’ve reserved a red or a green boat

  4. Exercises Reserves Sailors Boats Basic operations: Selection ( σ ) gives a subset of rows. Projection ( π ) Deletes unwanted cols. Cross-product(  ) combine two relations. Set-difference ( — ) Tuples in reln. 1, but not in reln. 2. Union(  ) Tuples in reln. 1 and in reln. 2. Additional operations: Intersection () – Tuples in both relns. Join ( ) – like  but only keep tuples where common fields equal Division ( / ) – tuples from reln 1 with matches in reln 2 Renaming ( ρ) – Rename columns Find sailors who’ve reserved a red and a green boat

  5. Exercises Reserves Sailors Boats Basic operations: Selection ( σ ) gives a subset of rows. Projection ( π ) Deletes unwanted cols. Cross-product(  ) combine two relations. Set-difference ( — ) Tuples in reln. 1, but not in reln. 2. Union(  ) Tuples in reln. 1 and in reln. 2. Additional operations: Intersection () – Tuples in both relns. Join ( ) – like  but only keep tuples where common fields equal Division ( / ) – tuples from reln 1 with matches in reln 2 Renaming ( ρ) – Rename columns Find the names of sailors who’ve reserved all boats

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