This document provides an overview of databases and SQL. It defines a database as an organized collection of logically related data. It discusses different types of data and how data is transformed into information. The document also outlines the major components of SQL, including DDL, DML, DCL, and TCL statements. DDL is used to define the database structure, DML manages data, DCL controls privileges, and TCL manages transactions. Common SQL commands like SELECT, INSERT, UPDATE, DELETE are also highlighted.

1. Er. Nawaraj Bhandari
Database

2. Module Database : Exam Pattern
 Global Exam : 50%
 Global Assignment : 50%

3. Module Database : Software
 MySQL
 Oracle
 SQL Server
 Access

4. What is a database?
“A database is a computerised record keeping
system”

5. Record Keeping Systems
 File system on a computer
 Word document
 Excel Spreadsheet
 Access database
 Manual card index file
 Files on a USB stick
 Are these all databases?

6. Database Functions
 Databases should be able to:
 Store
 Manipulate
 Retrieve

7. Database Size - 1
 Databases range in size:
 Single user databases on a PC
 Small office database with everyone doing the same
sorts of tasks
 Medium size database system with core data but
people doing different tasks
 Corporate databases spread over many sites
 Very large databases and data-warehouses

8. But databases aren’t like buckets!
 Database systems are not
just a mass of data
 It isn’t just about what they
can hold
 They are organised
 So we need a more precise
definition

9. More Detailed Definition
“We define a database as an organised collection
of logically related data”.

10. What does this mean?
 Organised
 Logically related
 Data

11. Organised
 Data is structured so as to be easily stored,
manipulated and retrieved by users.
 It is no good just having some data if we don’t
know how to get it in order to look at it and use it.

12. Related
 Pieces of data do not exist in isolation
 For example:
 In a salesperson’s database, it is natural for the
customer’s name and the customer’s address to be
stored together
 They are related
 Together, with other data about the customer, they are
part of a meaningful set

13. Data
 Data are any raw facts, numbers, or text that can be processed by a
computer.
 Data can be found in different formats :
1. operational or transactional data such as, sales, cost, inventory,
payroll, and accounting
2. nonoperational data such as forecast data
3. meta data - data about the data itself, such as logical database
design or data dictionary definitions

14. Types of Data
1. Traditional
a. Text such as names, address etc.
b. Numbers such as age, roll number, number of friends, etc.
c. Dates such as a date of birth, college enrolled date, exam date,
etc.
2. Multi-media
a. Images
b. Sounds
c. Video

15. Data and Information
 There is a little distinction between ‘data’ and ‘information’
 Data are ‘raw facts’.
Bagum, Ammena 01.02.81 97327627
Ako, Sarah 08.08.81 98737373
Finkle, Clive 09.09.81 93838383
Mc Farren, Debra 01.01.80 98383837
Sinseros, Douglas 27.05.80 99344222

16. Information
 Information is data that has been processed in such a way that it can
increase the knowledge of the person who uses it.
Student Name Date of Birth Student ID
Bagum, Ammena 01.02.81 97327627
Ako, Sarah 08.08.81 98737373
Finkle, Clive 09.09.81 93838383
Mc Farren, Debra 01.01.80 98383837
Sinseros, Douglas 27.05.80 99344222

17. Information is Important
 Economically
 Politically
 Personally
 Databases are the key to information.

18. SQL
Structured Query Language

19. SQL is a Standard
 SQL(Structural Query Language) is an ANSI (American National
Standards Institute) standard computer language for accessing and
manipulating database systems.
 SQL statements are used to retrieve and update data in a database.
 SQL works with database programs like MS Access, DB2, Informix, MS
SQL Server, Oracle, Sybase, etc.

20. SQL Database Tables
 A database most often contains one or more tables. Each table is
identified by a name (e.g. “Workers" or “Departments"). Tables
contain records (rows) with data.
 Below is an example of a table called “Workers":
LastName FirstName Jobtitle Age
Surani Lawrence Manager 56
Argo Emily 32
Villa Ahmed Packer 25
Manager

21.  With SQL, we can query a database and have a result set returned.
 A query like this:
 SELECT LastName FROM workers
 Gives a result set like this:
SQL Queries
LastName
Surani
Argo
Villa

22. Select all record from workers tables
 SELECT * FROM workers
SQL Queries

23. • Data Definition Language(DDL)
• Data Manipulation Language (DML)
• Data Control Language (DCL)
• Transaction Control (TCL)
SQL COMMANDS

24. DDL statements are used to define the database structure or
schema
Data Definition Language(DDL)
• CREATE: to create objects in the database
• ALTER: updates the structure of the database
• DROP - delete objects from the database
• TRUNCATE - remove all records from a table, including all
spaces allocated for the records are removed
• COMMENT - add comments to the data dictionary

25. DML statements are used for managing data within schema
objects.
Data Manipulation Language (DML)
• SELECT - retrieve data from the a database
• INSERT - insert data into a table
• UPDATE - updates existing data within a table
• DELETE - deletes all records from a table, the space for
the records remain
• MERGE - UPSERT operation (insert or update)
• CALL - call a PL/SQL or Java subprogram
• EXPLAIN PLAN - explain access path to data
• LOCK TABLE - control concurrency

26. Data Control Language (DCL)
• GRANT - gives user's access privileges to database
• REVOKE - withdraw access privileges given with the
GRANT command

27. TCL statements are used to manage the changes made by DML
statements. It allows statements to be grouped together into
logical transactions.
Transaction Control Language (TCL)
• COMMIT - save work done
• ROLLBACK - restore database to original since the last
COMMIT
• SAVEPOINT - identify a point in a transaction to which
you can later roll back
• SET TRANSACTION - Change transaction options like
isolation level and what rollback
segment to use

28. ANY QUESTIONS?