2. 1. What is DBMS?
“A Database Management System (DBMS) is a
program that controls creation, maintenance and use
of a database. DBMS can be termed as File
Manager that manages data in a database rather
than saving it in file systems”.
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5. What is RDBMS?
RDBMS stands for Relational Database Management
System.
RDBMS store the data into the collection of tables,
which is related by common fields between the columns
of the table. It also provides relational operators to
manipulate the data stored into the tables.
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6. 3. What is SQL?
SQL stands for Structured Query Language , and it
is used to communicate with the Database. This is a
standard language used to perform tasks such as
retrieval, updation, insertion and deletion of data
from a database.
Standard SQL Commands are Select.
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7. 4. What is a Database?
Database is nothing but an organized form of data
for easy access, storing, retrieval and managing of
data. This is also known as structured form of data
which can be accessed in many ways.
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8. What are tables and Fields?
A table is a set of data that are organized in a model with
Columns and Rows. Columns can be categorized as
vertical, and Rows are horizontal.
A table has specified number of column called fields but
can have any number of rows which is called record.
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9. TYPE OF KEY IN DBMS
KEY
PRIMERY
KEY
SUPER KEY
CANDIDATE
KEY
FOREIGN
KEY
ALTERNATE
KEY
COMPOUND
KEY
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10. Primary Key
Primary key is a set of one or more fields/columns of a table
that uniquely identify a record in database table. It can not
accept null, duplicate values. Only one Candidate Key can be
Primary Key.
Super Key
Super key is a set of one or more than one keys that can be
used to identify a record uniquely in a table.
Candidate Key
A Candidate Key is a set of one or more fields/columns that
can identify a record uniquely in a table. There can be multiple
Candidate Keys in one table. Each Candidate Key can work as
Primary Key.
Foreign Key
Foreign Key is a field in database table that is Primary key in
another table. It can accept multiple null, duplicate values.
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12. What is a join?
An SQL JOIN clause is used to combine rows from
two or more tables, based on a common field
between them.
DIFFERENT TYPE OF JOINS
INNER JOIN: Returns all rows when there is at least
one match in BOTH tables
LEFT JOIN: Return all rows from the left table, and
the matched rows from the right table
RIGHT JOIN: Return all rows from the right table,
and the matched rows from the left table
FULL JOIN: Return all rows when there is a match in
ONE of the tables
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