Codes

Error with v$instance

If your pl/sql code is utilizing v$instance and ended up with an error on build/compile:

PL/SQL: ORA-00942: table or view does not exist

Then all you have to do to fix this is:

GRANT SELECT ON v_$instance TO Schema_Name;

 

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Overloading

Overloading, can be achieved in a class by differentiating in:

  1. Number of arguments
  2. Order of arguments
  3. Type of arguments

Cannot create instance of the abstract or interface

Though Abstract classes can contain constructors and the compiler wont raise exception, but when creating object of abstract class the code wont compile, will state error as “Cannot create as instance of the abstract class or interface”

Error Code:

namespace n1
{
abstract class c1
{
public c1()
{
Console.WriteLine("c1");
}
}


class c2: c1
{
public c2()
{
Console.WriteLine("c2");
}
static void Main()
{
c2 c = new c1();
System.Console.ReadLine();
}
}
}

Oracle WebLogic Server: Clean cache

Follow the steps:

Stop WebLogic server (if in running mode)

Go to location, for WebLogic 9.x and higher versions:
C:\bea\user_projects\domains\yourdomain\servers\yourserver\tmp

Issue command to clear the cache:
rd C:\bea\user_projects\domains\yourdomain\servers\yourserver\tmp \s
or
simply you could delete the ‘tmp’ folder

Start WebLogic Server

Source [wlatricksntips]

Oracle Session Environment Parameters

To display all environment variable values for a given oracle session simply use below command

owa_util.print_cgi_env;

Abstraction & Encapsulation?

Abstraction

Encapsulation

1. Abstraction solves the problem in the design level.

1. Encapsulation solves the problem in the implementation level.

2. Abstraction is used for hiding the unwanted data and giving relevant data.

2. Encapsulation means hiding the code and data into a single unit to protect the data from outside world.

3. Abstraction lets you focus on what the object does instead of how it does it

3. Encapsulation means hiding the internal details or mechanics of how an object does something.

4. Abstraction- Outer layout, used in terms of design.

For Example:- Outer Look of a Mobile Phone, like it has a display screen and keypad buttons to dial a number

4. Encapsulation- Inner layout, used in terms of implementation.

For Example:- Inner Implementation detail of a Mobile Phone, how keypad button and Display Screen are connect with each other using circuits.

Real World Example:-

Take an example of Mobile Phone:-

You have a Mobile-phone you can dial a number using keypad buttons. Even you don’t know how these are working internally. This is called Abstraction. You have the only information that is needed to dial a number but not its internal working of mobile.

But how the Mobile Phone internally working?, how keypad buttons are connected with internal circuit? is called Encapsulation.