3i Infotech Placement: Sample Questions 322 - 324 of 1245
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Question 322
Explanation
- Tables cannot have multi-valued dependencies on a Primary Key.
- A relation schema R is said to be in 4NF if for every Multivalued dependency X Y that holds over R, one of following is true
- X is subset or equal to (or) XY = R.
- X is a super key.
Question 323
Explanation
- “Statement” provides methods to execute queries on the the database.
- Statement interface is a factory of ResultSet.
- Provides factory method to get the object of ResultSet.
Methods of Statement interface:
- Public ResultSet executeQuery
- Used to execute SELECT query.
- Return the object of ResultSet
- Public int executeUpdate
- Used to excute specified query.
- It create, drop, insert, update, delete.
Used to execute batch of commands.
- Public boolean execute
- Used to execute queries that may return multiple results.
- Public int [] executeBatch
Question 324
Question MCQ▾
A postal truck leaves its station and heads for Chicago, averaging 40mph. An error in the mailing schedule is spotted and 24 minutes after the truck leaves, a car is sent to overtake the truck. If the car averages 50mph then how long will it take to catch the postal truck?
Choices
Choice (4) | |
---|---|
a. | 1.5 hours |
b. | 1.6 hours |
c. | 2 hours |
d. | 3 hours |
Answer
c.Explanation
A postal truck leaves the station and heads for Chicago, averaging 40 mph.
An error in the mailing schedule is spotted and 24 minutes after the truck leaves, a car is sent to overtake the truck. The speed of car is 50mph.
Distance covered by both truck and car is same.
Let time taken by truck is x minutes and car is taking minutes.
So, Car will take 2 hours time to catch the postal truck.