ER and Relational Models

Question 61

In RDBMS, which type of Join returns all rows that satisfy the join condition?

• Inner Join
• Outer Join
• Semi Join
• Anti Join

Question 62

A many-to-one relationship exists between entity sets r 1 and r 2 . How will it be represented using functional dependencies if Pk(r) denotes the primary key attribute of relation r ?

• Pk(r₁ ) → Pk(r ₂)
• Pk(r₂ ) → Pk(r ₁ )
• Pk(r₂ ) → Pk(r₁ ) and Pk(r ₁ ) → Pk(r ₂ )
• Pk(r ₂ ) → Pk(r₁ ) or Pk(r ₁ ) → Pk(r ₂)

Question 63

Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram ?

• Diamonds with double/bold border
• Rectangles with double/bold border
• Ovals with double/bold border
• Ovals that contain underlined identifiers

Question 64

Given the relations employee (name, salary, dept-no), and department (dept-no, dept-name,address) Which of the following queries cannot be expressed using the basic relational algebra operations (σ, π, x, -, ∪, p)

• Department address of every employee
• Employees whose name is the same as their department name
• The sum of all employees\' salaries
• All employees of a given department

Question 65

In E-R model, Y is the dominant entity and X is subordinate entity

• If X is deleted, then Y is also deleted
• If Y is deleted, then X is also deleted
• If Y is deleted, then X is not deleted
• None of the above

Question 66

Let R₁ (a, b, c) and R₂ (x, y, z) be two relations in which a is the foreign key of R₁ that refers to the primary key of R₂ . Consider following four options. (a)Insert into R ₁ (b)Insert into R ₂ (c)Delete from R ₁ (d)Delete from R ₂ Which of the following is correct about the referential integrity constraint with respect to above?

• Operations (a) and (b) will cause violation.
• Operations (b) and (c) will cause violation.
• Operations (c) and (d) will cause violation.
• Operations (d) and (a) will cause violation.

Question 67

How to express that some person keeps animals as pets?

• (A)
• (B)
• (C)
• (D)

Question 68

A view of database that appears to an application program is known as

• Schema
• Subschema
• Virtual table
• None of these

Question 69

Which operation is used to extract specified columns from a table?

• Project
• Join
• Extract
• Substitute

Question 70

The relation schemas R₁ and R₂ form a Lossless join decomposition of R if and only if: (a) R₁ ∩ R₂ ↠ (R₁ - R₂) (b) R₁ → R₂ (c) R₁ ∩ R₂ ↠ (R₂ - R₁ ) (d)(R₂ → R₁) ∩ R₂

• (a) and (b) happens
• (a) and (d) happens
• (a) and (c) happens
• (b) and (c) happens