Relational Algebra 2

What is the main purpose of relational algebra in the context of databases?

• To define the schema of the database

• To provide a formal foundation for relational database operations

• To design the user interface of a database application

• To establish foreign key relationships between tables

Which relational algebra operation is used to select certain column from the table/relations?

• Project (π)

• Select (σ)

• Rename (ρ)

• Join (⨝)

Which relational algebra operation is used to select rows that satisfy a given predicate?

• Project (π)

• Select (σ)

• Rename (ρ)

• Join (⨝)

What is the purpose of the Rename operation in relational algebra?

• To merge two tables

• To modify data values

• To change the names of attributes in a relation

• To filter specific rows

Which operation is appropriate for extracting rows that meet a certain condition and only specific columns?

• Select then Project

• Project then Select

• Join then Divide

• Divide then Rename

Which operation combines rows from two or more tables based on a related column between them?

• Set Join

• Intersection

• Join

• Union

What type of join automatically merges tables based on all columns with the same name and datatype in both tables?

• Inner Join

• Natural Join

• Outer Join

• Cross Join

In relational algebra, how would you describe a Select operation with a condition 'age > 30' on a table 'Employees'?

• π_age>30(Employees)

• ρ_age>30(Employees)

• δ_age>30(Employees)

• σ_age>30(Employees)

What is the result of applying the Project operation π_name, department(Employees) on a table Employees?

• A table that combines information from the Employees and another table.

• A table renamed to 'name, department'

• A table with the 'name' and 'department' columns, containing unique combinations of these fields.

• A table without the 'name' and 'department' columns, containing unique combinations of these fields.

Below are the types of joins, except

• Inner Join

• Outer Join

• Left Join

• Outline Join