Relational algebra is a
Answer: D) None of the above
Relational Algebra is a procedural query language used in relational database management systems (RDBMS). It provides a set of mathematical operations to retrieve and manipulate data stored in relational tables.
Some common operations of Relational Algebra are:
* Selection (σ): Selects specific rows from a table.
* Projection (π): Selects specific columns from a table.
* Union (∪): Combines records from two compatible tables.
* Join (⋈): Combines related data from two or more tables.
* Difference (−): Finds records present in one relation but not in another.
The given options describe different forms of representing relationships between entities. These descriptions are more closely related to an Entity-Relationship (E-R) Model, not Relational Algebra.
Relational Algebra भनेको Database मा रहेका Data हरूलाई खोज्न, छान्न र आवश्यकताअनुसार मिलाउन प्रयोग गरिने एउटा Mathematical Query Language हो। यसले विभिन्न Mathematical Operations प्रयोग गरेर Relational Database का Table हरूबाट आवश्यक जानकारी निकाल्न मद्दत गर्छ।
यसका केही प्रमुख Operations यस प्रकार छन्:
* Selection (σ): Table बाट आवश्यक Row मात्र छान्ने।
* Projection (π): Table बाट आवश्यक Column मात्र छान्ने।
* Union (∪): दुईवटा मिल्दो Table का Records एकै ठाउँमा जोड्ने।
* Join (⋈): सम्बन्धित Table हरूको Data जोड्ने।
* Difference (−): एउटा Table मा भएका तर अर्को Table मा नभएका Records पत्ता लगाउने।
दिइएका विकल्पहरूमा Entity हरूबीचको सम्बन्धलाई Symbolic, Graphical वा Diagrammatic रूपमा प्रस्तुत गर्ने कुरा गरिएको छ। यी विवरणहरू Relational Algebra भन्दा E-R Model (Entity-Relationship Model) सँग सम्बन्धित छन्।
त्यसैले दिइएको प्रश्नमा सही विकल्प छैन जस्तो देखिन्छ।
Exam Tip:
* Relational Algebra: Mathematical operations used to retrieve and manipulate database data.
* E-R Model: Graphical representation of entities, attributes and relationships.