db-class-excerpt
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===== Relational Algebra 2 ===== | ===== Relational Algebra 2 ===== | ||
- | **Union** Operator: Problem with × and ⋈ is that they try to match tuples (rows) form the relations (tables). | + | **Union** Operator: Problem with × (cross product) |
π< | π< | ||
- | Stanford\\ | + | Stanford |
- | Susan\\ | + | Susan |
- | Cornell\\ | + | Cornell |
- | Mary\\ | + | Mary |
- | John\\ | + | John |
... | ... | ||
db-class-excerpt.1318268152.txt.gz · Last modified: 2023/04/12 20:44 (external edit)