Important Notes related subject code 802

Q1.    What is RDBMS?

Or

          What is concept of RDBMS?

Or

          What do you mean RDBMS?

Or

Explain
RDBMS Database.

Ans. Stands for
"Relational Database Management System." An RDBMS is a DBMS designed specifically for relational databases. Therefore, RDBMS is a subset of DBMS.

A relational database
refers to a database that stores data in a structured format,
using rows and columns. This makes it
easy to locate and access specific values within the database. It is
"relational" because the values within each table are related to each other. Tables may also be
related to other tables. The relational structure makes it possible to
run queries across multiple tables at once.

While a relational
database describes the type of database an RDMBS manages, the RDBMS refers to
the database program itself. It is the software
that executes queries on the data, including adding, updating, and searching
for values. An RDBMS may also provide a visual representation of the data. For
example, it may display data in a tables like a spreadsheet, allowing
you to view and even edit individual values in the table. Some RDMBS programs
allow you to create forms that can streamline entering, editing, and deleting
data.

Most well known
DBMS applications fall into the RDBMS category. Examples
include Oracle Database, MySQL, Microsoft SQL Server, and IBM DB2. Some of
these programs support non-relational databases, but they are primarily used
for relational database management.

Examples of
non-relational databases include Apache HBase, IBM Domino, and Oracle NoSQL
Database. These type of databases are managed by other DMBS programs that
support NoSQL, which do not fall into the RDBMS
category.

Q.2    What is table?

Ans. Generally
Table is a collection of similar objects where similar data are stored.

for example if you want to keep data
of different books then you made a table for book and if you want to keep data
of another type of object like: Pen then you make a table for a pen.

Tables are added in database as new
type of object is need to keep track of.

Q.3    What
is tuple?

Or

          What
is use of tuple in database?

Or

          What
do you mean by rows?

Ans. A
table has rows and columns, where rows represents records and columns represent
the attributes. Tuple − A single row of a table, which contains a single record
for that relation is called a tuple. Relation instance − A finite set of tuples
in the relational database system represents relation instance.

Q.4    What is field?

Or

          What is column in
database?

Or

          Explain field element in
database?

Ans. A database is a
collection of tables. Each table has fields, or containers, to hold the
data. 

Q.5    What
is a Relation Schema?

Ans.
A relation schema describes the structure
of the relation, with the name of the relation(name of table), its attributes
and their names and type.

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Q.6    What
is a Relation Key?

Ans.
A relation key is an attribute which can
uniquely identify a particular tuple(row) in a relation(table).

Q.7    What
is Java programming language?

Ans. Java is a general-purpose computer programming
language that is concurrent,
class-based, object-oriented, and specifically designed to have as few
implementation dependencies as possible. It is intended to let application
developers “write once, run anywhere” (WORA), meaning
that compiled Java code can run on all platforms that support Java without the
need for recompilation.

For example, you can
write and compile a Java program on UNIX and run it on Microsoft Windows,
Macintosh, or UNIX machine without any modifications to the source code. WORA is achieved by compiling a Java
program into an intermediate language called bytecode.
The format of bytecode is platform-independent. A virtual machine, called the Java Virtual Machine
(JVM), is used to run the bytecode on each platform.

Q.8    What
is an operator in java language?

Or

          What
is use of operator in java language?

Ans. An operator is a symbol that performs a
specific kind of operation on one, two, or three operands, and
produces a result. The type of the operator and its operands determines the
kind of operation performed on the operands and the type of the result
produced.

Q.9    What is array in java
language?

Ans.  An array is
a container object that holds a fixed number of values of a single type. The
length of an array is established when the array is created. After creation,
its length is fixed. You have seen an example of arrays already, in the main method of the "Hello
World!" application. This section discusses arrays in greater detail.

 

Q.10  What do you understand Wrapper classes in java?

Ans. Java provides type
wrappers, which are classes that encapsulate a primitive
type within an object. In Java, we have 8 primitive data types.

A wrapper class wraps
(encloses) around a data type and gives it an object appearance. Wherever, the
data type is required as an object, this object can be used. Wrapper classes
include methods to unwrap the object and give back the data type.

The type
wrappers classes are part of java.lang package.

Each primitive type has
a corresponding wrapper class.

Primtive Type	Wrapper Class
double	Double
float	Float
long	Long
int	Integer
short	Short
byte	Byte
char	Character
boolean	Boolean

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