3i Infotech Placement: Sample Questions 23 - 25 of 1245

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Question 23

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Short Answer▾

What does error ‘NULL pointer assignment’ mean and what causes this error?

Explanation

  • NULL pointer error happens when the program tries to store value in the location pointed to by the NULL pointer.
  • A null pointer assignment is a runtime error.

Question 24

Question

MCQ▾

Can an Integrity Constraint be enforced on a table if some existing table data does not satisfy the constraint?

Choices

Choice (4)

a.

Yes

b.

No

c.

None of the above

d.

All of the above

Answer

b.

Explanation

Overview of Integrity Constraints
  • No, an integrity cannot Constraint cannot be enforced on a table if some existing table data does not satisfy the constraint.
  • Integrity constrain are used to accuracy and consistency of data in a rational database.
  • Data integrity is handled in a relational database using referential integrity.

Below the types of integrity constrains:

  • UNIQUE
    • To sure about a given column is unique
  • NOT NULL
    • To sure about that no null values are allowed
  • FOREIGN KEY
    • To sure two keys share a primary key to foreign key relationship.
The Types of Integrity Constrains

Question 25

Question

MCQ▾

POST-BLOCK trigger is a … .

Choices

Choice (4)

a.

Navigational trigger

b.

Key trigger

c.

Transactional trigger

d.

None of the above

Answer

a.

Explanation

Example of Post-Block Trigger
  • A navigational trigger
  • Fires when the focus moves off the current block.
  • Used to bring block՚s current record, to a condition or to prevent the user from leaving a block based on condition.
  • Form is set to put the cursor a particular block.
  • Form builder attempts to put the cursor at a target location, if the target is outside of the current unit.
  • Does not fire when the validation unit form document property it is set to form.

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