# Database [3i Infotech Placement]: Sample Questions 264 - 266 of 294

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## Question 264

Database
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### Describe in Detail

Essay▾

What is 1 NF (Normal Form) ?

### Explanation

• The domain of attribute must include only atomic (simple, indivisible) values.

1NF (First Normal Form) Rules

• Each table cell should contain a single value.
• Each record needs to be unique.

1NF Example:

• Understanding the example of above Normalization table
 Full Name Physical Address MOVIES RENTED SALTUTATION Janat First Street Plot No 4 Pirates of the Caribbean Ms. Janat First Street Plot No 4 Clash of the Titans Ms. Rohit 3rd Street 34 Forgetting Sarah Marshal Mr. Rohit 3rd Street 34 Daddy՚s Little Girls Mr. Rohit 5th Avenue Clash of the Titans Mr.

## Question 265

Database

### Question

MCQ▾

A B C is a set of attributes. The functional dependency is a follows:

AB B

AC C

C B

Choice (4)

a.

Is in 3NF

b.

Is in BCNF

c.

Is in 2NF

d.

Is in 1NF

d.

### Explanation

 {A, B, C}AC is the primary key Neither C is a key nor B is a prime attributeSo, it is not 3NF
• Now, B is not functionally dependent on key AC
• So, it is not in 2NF
• Hence, given functional dependency is 1 NF.

## Question 266

Database
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Appeared in Year: 2006

### Describe in Detail

Essay▾

What is the difference among “dropping a table” “truncating a table” and “deleting all records” from a table?

### Explanation

Drop Table

• It will remove the existence of the table from the database along with its data and structure and all the constraints.
• The table will be no longer available.
• This is a DDL Statement.

Truncate Table

• It will remove all the rows from a table.
• It will not delete the table. It is a DDL statement that means the deleted rows cannot be reverted back by ROLLBACK statement.
• It will only be used if users needs to delete the entire rows from a tables.
• No conditions will be applied in Truncate.

Delete Table

• It is a DML statement which will delete rows from a table according to the matching criteria mentions in the ‘where’ clause and these rows can be reverted back by ‘ROLLBACK’ statement if ‘COMMIT’ is not fired.
• Delete statement will used in both the cases, eitehr selected rows or entire rows from tables.

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