Database Management System

Running head: DATABASE MANAGEMENT SYSTEM
Database Management System
Name of the Student
Name of the University
Author’s Note:

1DATABASE MANAGEMENT SYSTEM
Table of Contents
Task 1: Structure Query Language.................................................................................................2
1.1 Data Manipulation Language:...............................................................................................2
1.2 Data Control Language:.........................................................................................................4
Task 2: Data Manipulation..............................................................................................................6
Task 3: Database Testing...............................................................................................................10
3.1 Database Testing Definition and Importance:.....................................................................10
3.2 Testing Process:...................................................................................................................11
Bibliography:.................................................................................................................................13

2DATABASE MANAGEMENT SYSTEM
Task 1: Structure Query Language
1.1 Data Manipulation Language:
The DML or data manipulation language is a computer language that offers the user way
to write data manipulation commands within a database management system. The data
manipulation includes the data insertion within the database relations, fetching the existing data
from the database, eliminating data from the relations and updating the stored data. The basic
idea behind the DML is same for all the relational databases. The data manipulation language
can be of two types such as procedural programming and declarative programming. In the
procedural programming, the user specifies the desired data and the process of retrieving it.
However, in the declarative programming, the user will mention the required data. The
commands for data manipulation are select, inert, update and delete. The select, update and
delete commands specifies which data to be manipulated and form where we can access the data.
The insert command mentions which data to be inserted and into which position. From and
where are associated with the select and delete commands. The form specifies a single relation
within the database and the attributes mentioned in the delete or select command should be
existing within that specific relation. Where is for implementing condition within the query. The
where clause restricts the commands to specific value or values within the relation mentioned in
the form syntax. Taken as an example, select * from student where student.city = ‘Sydney’. This
query searches all the records in the student relation based on the condition that student must be
living in Sydney.
Update: Update command uses the Set and Where clauses to manipulate the data within a
database. However, there are some restrictions regarding data update. One of the most important

3DATABASE MANAGEMENT SYSTEM
restriction is that primary key of a relation cannot be updated. Another important update is that
foreign key of a relation cannot be updated to some value which is not present as primary key of
referenced relation. Update command syntax is as following.
UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;
One important thing to remember is running the query without mentioning the where
clause will result into updating all the values in that attribute. The example of update command
is as following.
Update employees first_name = 'Jhon' Where emp_no = 10001;
Delete: This command is used for deleting the present record within the database. The
form of writing the delete query in relational database is
DELETE FROM table_name WHERE condition.
It is mandatory to specify the where condition in the delete command. If the where
condition is not mentioned then few database management system may delete all records within
the database. Taken as an example as following.
Delete from employees Where emp_no = 10001;