Relational Algebra Basics - 1 Video Lecture | Question Bank for GATE Computer Science Engineering - Computer Science Engineering (CSE)

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FAQs on Relational Algebra Basics - 1 Video Lecture - Question Bank for GATE Computer Science Engineering - Computer Science Engineering (CSE)

1. What is relational algebra?
Relational algebra is a procedural query language used to query and manipulate relational databases. It provides a set of operations to perform various operations like selection, projection, union, intersection, and join on tables in a database.
2. What are the basic operations in relational algebra?
The basic operations in relational algebra include selection, projection, union, set difference, cartesian product, and join. Selection is used to retrieve specific rows based on a given condition, projection is used to retrieve specific columns from a table, union combines two tables and removes duplicates, set difference returns the records that are present in one table but not in another, cartesian product returns all possible combinations of rows from two tables, and join combines two tables based on a common attribute.
3. How does selection operation work in relational algebra?
The selection operation in relational algebra is used to retrieve specific rows from a table that satisfy a given condition. It is denoted by the sigma (σ) symbol. The condition is specified using logical operators such as equality (=), inequality (!=), less than (<), greater than (>), etc. The result of the selection operation is a new table that contains only the rows that meet the specified condition.
4. What is the difference between union and intersection operations in relational algebra?
The union operation in relational algebra combines two tables and removes any duplicate rows, resulting in a new table that contains all the distinct rows from both tables. On the other hand, the intersection operation returns only the common rows between two tables, disregarding any duplicates. In other words, the union operation combines rows from both tables, while the intersection operation only includes rows that exist in both tables.
5. How does the join operation work in relational algebra?
The join operation in relational algebra combines two tables based on a common attribute or set of attributes. It is denoted by the join (⨝) symbol. The join operation creates a new table by concatenating the rows from both tables where the values in the common attribute(s) match. There are different types of join operations, such as inner join, left join, right join, and full outer join, which determine how the non-matching rows are included in the result.
58 videos|7 docs|165 tests
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