Interview Questions

Oracle supports 3 transaction isolation levels: 

- Read committed (default)

- Serializable transactions

- Read only

- A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index.

- A non clustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows on disk. The leaf node of a non clustered index does not consist of the data pages. Instead, the leaf nodes contain index rows.

Basically there are many standards of Wi-Fi in the industry but some popular of them are 802.11a, 802.11b, 802.11g/n. With the support of these Wi-Fi protocols we can communicate/interact among the devices at the speed of 5Ghz to 2.4Ghz dual band communication.

If we have Wi-Fi nic card so firstly we have to install their drivers and after installation if we have Wi-Fi access point then we can see the signal strength in the right corner below just open that and find the access point to connect, if access point is configured with the security, type the key to connect and enjoy the service.

Wi-Fi is technically referred to as the 802.11 protocol. Over time, Wi-Fi has improved, giving rise to different variations of the protocol.

802.11a – This version operates at 54Mbps. It is considered as the favorite wireless LAN protocol for IP telephony.

1 : InnoDB provides us row level locking while MyISAM provides us table level locking.

2 : InnoDB offers foreign key constraints wheres in MyISAM does not have foreign key constraints.

3 : InnoDB does not have full text search wheres MyISAM provides us full text search.

- ABS(number)

Returns the absolute positive value of an expression.
Syntax:
ABS(expression)
Example:
SELECT ABS(-1.0), ABS(0.0), ABS(1.0)
Output:
1.0    .0    1.0

- CEIL(number)

Returns the smallest integer greater than, or equal to, the specified numeric expression.
Syntax:
CEILING(expression)
Example:
SELECT CEILING($223.45), CEILING($-223.45), CEILING($0.0)
Output:
224.00    -223.00        0.00

- FLOOR(number)

Returns the largest integer less than, or equal to, the specified numeric expression.
Syntax:
FLOOR(expression)
Example:
SELECT FLOOR($223.45), CEILING($-223.45), CEILING($0.0)
Output:
223.00      -224.00        0.00

- MOD(number, divisor)

Returns the remainder of the division from 2 integer values.
Syntax:
MOD(dividend, divisor)
Example:
SELECT MOD(20,3)
Output:
2

- POWER(number, power)

Returns the exponential value for the numeric expression.
Syntax:
POWER(number, power)
Example:
SELECT POWER(2.0, 3.0)
Output:
8.0

- SIGN(number)

Returns the sign i.e. positive or negative value for the numeric expression. It returns -1 for negative expressions, a value of 0 for zero
Syntax:
SIGN(number)
Example:
SELECT SIGN(4)
Output:
1

- ROUND(number, precision)

Returns the numeric value rounded off to the next value specified.
Syntax:
ROUND(number, number of places)
Example:
SELECT ROUND(1.3456, 2)

- SQRT(number)

Returns the square root value of the expression.
Syntax:
SQRT(number)
Example:
SELECT SQRT(4.0)
Output:
2.0

- TRUNC(number, precision)

Returns a numeric value that truncate to the specific places
Syntax:
TRUNCATE(number,places)
Example:
SELECT TRUNCATE(1.3456, 2)
Output:
1.34

AWT are heavy-weight componenets. Swings are light-weight components. Hence swing works faster than AWT.

unlink()-deletes the given file from the file system.
unset() -makes a variable undefined.