Both these are used to combine the results of different SELECT statements.

    UNION       - Selects only distinct values 

    UNION ALL - Selects duplicate values also

Syntax:

    SELECT column_name(s) FROM table1

    UNION / UNION ALL

    SELECT column_name(s) FROM table2;

Notice that each SELECT statement within the UNION must have the same number of columns. The columns must also have similar data types. Also, the columns in each SELECT statement must be in the same order.

Use SELECT DISTINCT ..... in DB2 query

The DISTINCT keyword can be used to return only distinct (different) values.

Syntax:

     SELECT DISTINCT column1,column2

      FROM table_name;

Marshalling is the process of gathering data from one or more applications or non-contiguous sources in computer storage, putting the data pieces into a message buffer, and organizing or converting the data into a format that is prescribed for a particular receiver or programming interface.  

1. Have two indexes pointing to two ends of array, say i and j.

2. Approach towards each other with a check condition that they dont cross each other.

3. Each iteration of while loop, swap the numbers pointed by two indexes when num[i] index number is not equal to 1.

void sort()

{

     int a[]={1,0,0,0,1,1,0,1,0,1,0,0,1,0};

     int i=0;

     int j=13;

     int temp;

      while(j>i)

     {

          if(a[i]==1)

                 i++;

          if(a[j]==0)

                 j--;

          if(a[i]==0)

         {

                 temp=a[i];

                a[i]=a[j];

                a[j]=temp;

         }

     } 

     for(i=0;i<14;i++)

             Console.Write(a[i]+", ");

}

Output: 1,1,1,1,1,1,0,0,0,0,0,0,0

A stored procedure is a segment of declarative SQL statements stored inside the database catalog. A stored procedure can be invoked by triggers, other stored procedures or applications such as Java, C#, PHP, etc.

Advantages 

- Typically stored procedures help increase the performance of the applications. Once created, stored procedures are compiled and stored in the database. However MySQL implements the stored procedures slightly different. MySQL stored procedures are compiled on demand. After compiling a stored procedure, MySQL puts it to a cache. And MySQL maintains its own stored procedure cache for every single connection. If an application uses a stored procedure multiple times in a single connection, the compiled version is used, otherwise the stored procedure works like a query.

- Stored procedures helps reduce the traffic between application and database server because instead of sending multiple lengthy SQL statements, the application has to send only name and parameters of the stored procedure.

- Stored procedures are reusable and transparent to any applications. Stored procedures expose the database interface to all applications so that developers don’t have to develop functions that are already supported in stored procedures.

- Stored procedures are secure. Database administrator can grant appropriate permissions to applications that access stored procedures in the database without giving any permission on the underlying database tables.

Disadvantages

- If you use a lot of stored procedures, the memory usage of every connection that is using those stored procedures will increase substantially. In addition, if you overuse a large number of logical operations inside store procedures, the CPU usage will also increase because database server is not well-designed for logical operations.

- A constructs of stored procedures make it more difficult to develop stored procedures that have complicated business logic.

- It is difficult to debug stored procedures. Only few database management systems allow you to debug stored procedures. Unfortunately, MySQL does not provide facilities for debugging stored procedures.

-It is not easy to develop and maintain stored procedures. Developing and maintaining stored procedures are often required specialized skill set that not all application developers possess. This may lead to problems in both application development and maintenance phases.

The main types of system calls are as follows:

Process Control: These types of system calls are used to control the processes. Some examples are end, abort, load, execute, create process, terminate process etc.

File Management: These types of system calls are used to manage files. Some examples are Create file, delete file, open, close, read, write etc.

Device Management: These types of system calls are used to manage devices. Some examples are Request device, release device, read, write, get device attributes etc.

Information Maintenance: These types of system calls are used to set system data and get process information. Some examples are time, OS parameters, id, time used etc.

Communications: These types of system calls are used to establish a connection. Some examples are send message, received messages, terminate etc

UDP (User Datagram Protocol) is a communications protocol that offers a limited amount of service when messages are exchanged between computers in a network that uses the Internet Protocol (IP).

A 32 bit processor is faster than a 64 bit processor, 64 bit processors are very commonly used that you can find it easily in any home pc but the main difference is the hardware you are having on your machine. For 32 bits there isn't any need of any wide main bus to carry 32 bits at a time but for 64 bits its must that you should have a wider bus to carry 64bits.