This question tests the understanding of relational algebra operations: projection ($\pi$), selection ($ \sigma$), set difference (-), and intersection ($ \cap$). 1. Selection ($\sigma$): Filters rows based on a condition. 2. Projection ($\pi$): Selects specific columns. 3. Intersection ($\cap$): Returns common tuples from two relations. 4. Set Difference (-): Returns tuples from the first relation that are not present in the second. The process involves evaluating sub-expressions from innermost parentheses outwards. Due to inconsistencies found, it's assumed there might be a typo in the question. If we assume the left-side selection was `Name "MM"`, then the result is "JA".
Consider the following instance of a relation District - District Name Population JA 10 AJ 50 MM 5 Which of the District name will be returned by the following relational algebra expression? ($ \pi_{\text{Name}} (\sigma_{\text{Name}="Aj"} (\text{District}))) - [(\pi_{\text{Name}} (\sigma_{\text{Population}>5}(\text{District}))) \cap (\pi_{\text{Name}} (\sigma_{\text{Name} ="Aj"}(\text{District}))) ]$
Asked in Programmer Exam 2024 · Topic: Basics of Computers and Information Technology (Database Management Systems (DBMS) Basics: Concepts, Types of Databases)
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