Technology Questions

 - When two processes are waiting to update the rows of a table which are locked by another process, the situation is called a deadlock.
 - The reasons for it to happen are:
 * lack of proper row lock commands.
 * Poor design of front-end application
- It reduces the performance of the server severely.
- These locks get automatically released automatically when a commit/rollback operation is performed or any process is killed externally.

Open for INPUT, OUTPUT, I-O, EXTEND.

1.INPUT : for read only purpose

2.OUTPUT : for write only purpose

3.EXTEND : for appending records

4.I-O : for read and write(using EXTEND) purpose

Similarity: Both WHERE and HAVING Clause filters out records based on one or more conditions.

Difference: WHERE Clause can only be applied to a static non-aggregated column whereas HAVING is needed for aggregated columns.

A static method cannot access non static variables or methods because static methods doesnt need the object to be accessed. So if a static method has non static variables or non static methods which has instantiated variables they will no be intialized since the object is not created and this could result in an error.

A DB2 bind is a process that builds an access path to DB2 tables. 

WATER MARK is a divided segment of used and free blocks. Blocks which are below high WATER MARK i.e. used blocks, have at least once contained some data. This data might have been deleted later. Oracle knows that blocks beyond high WATER MARK don’t have data; it only reads blocks up to the high WATER MARK during a full table scan. 

In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from the receiver (okay to go ahead), and then sends the next frame.

Wrapper classes wrap primitive values in a class and offers utility to access them through objects. Some of the primitive wrapper data types are:

Byte, short, int, long, float, double, char, Boolean.

Example: 

Create a class name VectorAdd to populate it with integer values using the add(int, object) method.

public class VectorAdd

{

       public static void main(String argv[])

       {

             Vector v = new Vector();

             v.add(0,new Integer(10));

             v.add(1,new Integer(20));

             v.add(2,new Integer(30));

             for(int i=0; i < v.size();i ++)

             {

                  Integer iw =(Integer) v.get(i);

                  System.out.println(iw);

             }

       }

}