Technical Consultant Intern

1. While calling a function, we pass values of variables to it. Such functions are known as “Call By Values”. 
While calling a function, instead of passing the values of variables, we pass address of variables(location of variables) to the function known as “Call By References.

2. In Call by Value method, the value of each variable in calling function is copied into corresponding dummy variables of the called function. 
In Call by Reference method, the address of actual variables in the calling function are copied into the dummy variables of the called function.

3. With Call by Value method, the changes made to the dummy variables in the called function have no effect on the values of actual variables in the calling function. With Call by Reference method, using addresses we would have an access to the actual variables and hence we would be able to manipulate them.

In Java, the main point here is that the JVM depends on the operating system – so if you are running Mac OS X you will have a different JVM than if you are running Windows or some other operating system. This fact can be verified by trying to download the JVM for your particular machine – when trying to download it, you will be given a list of JVMs corresponding to different operating systems, and you will obviously pick whichever JVM is targeted for the operating system that you are running. So we can conclude that JVM is platform-dependent and it is the reason why Java is able to become “Platform Independent”.

Java System.out.println() is used to print an argument that is passed to it. The statement can be broken into 3 parts which can be understood separately as:
System: It is a final class defined in the java.lang package.
out: This is an instance of PrintStream type, which is a public and static member field of the System class.
println(): As all instances of PrintStream class have a public method println(), hence we can invoke the same on out as well. This is an upgraded version of print(). It prints any argument passed to it and adds a new line to the output. We can assume that System.out represents the Standard Output Stream.

The Collection in Java is a framework that provides an architecture to store and manipulate the group of objects. Java Collections can achieve all the operations that you perform on a data such as searching, sorting, insertion, manipulation, and deletion.
Java Collection means a single unit of objects. Java Collection framework provides many interfaces (Set, List, Queue, Deque) and classes (ArrayList , Vector, LinkedList , PriorityQueue , HashSet, LinkedHashSet, TreeSet).

1. DDL stands for Data Definition Language. DML stands for Data Manipulation Language.

2. DDL is used to create database schema and can be used to define some constraints as well. DML is used to add, retrieve or update the data.
 

3. DDL basically defines the column (Attributes) of the table. DML add or update the row of the table. These rows are called as tuple.
 

4. DDL doesn’t have any further classification. DML is further classified into Procedural and Non-Procedural DML.
 

5. Basic command present in DDL are CREATE, DROP, RENAME, ALTER etc. BASIC command present in DML are UPDATE, INSERT, MERGE etc.
 

6. DDL does not use WHERE clause in its statement. While DML uses WHERE clause in its statement.

1. Group by statement is used to group the rows that have the same value. Whereas Order by statement sort the result-set either in ascending or in descending order.

2. Group by may be allowed in CREATE VIEW statement. While Order by does not use in CREATE VIEW statement.
 

3. In select statement, Group by is always used before the order by keyword. While in select statement, it is always used after the group by keyword.
 

4. Attribute cannot be in the group by statement under aggregate function. Whereas in order by statement, attribute can be under aggregate function.