Technology Questions

- Friend classes are useful when a class wants to hide features from users which are needed only by another, tightly coupled class. 

- Implementation details can be kept safe by providing friend status to a tightly cohesive class.

A is wrong because a class can extend nly one class .B is wrong because a class can implement any number of interfaces.C is wronb because both can can be done simulteneously.So, D is correct

Default constructors has no arguments

If in application program IO-PCB is there then it is a online program. In ENTRY statement IO-PCB must be listed first and then DB-PCB.

The main aim of the namespace is to understand the logical units of the program and to make the program so robust.

Static (embedded) SQL:

1.In static SQL how database will be accessed is predetermined in the embedded SQL statement.

2.It is more swift and efficient.

3.SQL statements are compiled at compile time.

4.Parsing, validation, optimization, and generation of application plan are done at compile time.

5.It is generally used for situations where data is distributed uniformly.

6.EXECUTE IMMEDIATE, EXECUTE and PREPARE statements are not used.

7. It is less flexible 

Dynamic (interactive) SQL:

1.In dynamic SQL, how database will be accessed is determined at run time.

2.It is less swift and efficient.

3.SQL statements are compiled at run time.

4.Parsing, validation, optimization, and generation of application plan are done at run time.

5.It is generally used for situations where data is distributed non-uniformly.

6.EXECUTE IMMEDIATE, EXECUTE and PREPARE statements are used.

7.It is more flexible.

These two methods are bulid-in methods  in php. with  construct() we can overwride the parent class method. The inverse of the __construct() PHP capacity while making another class, is the __destruct() technique. The __destruct() technique will consequently keep running, after you've completed with the PHP class.