Database Introduction – SS1 Digital Technologies Lesson Note (Third Term)

A database is an organised collection of related data stored so that it is easy to search, change and manage.

Subject: Digital Technologies
Class: SS1

Behavioural objectives

By the end of the lesson, students should be able to:

1. Define a database and give examples.
2. State what a DBMS is and name common DBMS software.
3. List the things a DBMS does.
4. Explain what a table, a field and a record are.
5. Explain what a primary key is and give examples.

What is a database?

A database is an organised collection of related information (data) stored in a way that makes it easy to search, change and manage.

Think of a school office that keeps details of hundreds of students:

• Name: who the student is.
• Class: where the student belongs.
• Home address: where to reach the family.
• Grades: how the student is performing.

Kept on loose scraps of paper, this information is hard to find and easy to lose. Kept in a database, it is organised.

What are examples of a database?

• Phonebook: a database of names and phone numbers.
• Contacts app on your phone: a digital database of your friends and family.
• School register: a database of student attendance.
• Library card catalogue: a database of books.

Why use a digital database?

A digital database is faster and more reliable than a physical file.

• Fast searching: one student can be found among thousands in seconds.
• Easy updating: a change is made once and shows everywhere.
• Less repetition: the same detail is not written many times.
• Better security: access can be limited to the right people.
• Less space: no cabinets full of paper.

What is a DBMS?

A DBMS (Database Management System) is the software used to create, store, change and protect the data in a database.

The database is the data itself. The DBMS is the tool you use to work with that data.

• Database: like a bank vault, where the money is kept.
• DBMS: like the bank teller, who puts money in or takes it out for you.
• User: does not walk into the vault, but asks the teller.

What is the difference between a database and a DBMS?

A database is the stored collection of data. A DBMS is the software that manages that collection.

What are examples of DBMS software?

Common DBMS software includes Microsoft Access, MySQL and Oracle.

1. Microsoft Access: suited to beginners, schools and small businesses.
2. MySQL: a popular free DBMS used behind many websites.
3. Oracle: a large DBMS used by big organisations such as banks.

What does a DBMS do?

• Create: sets up a new place to store data.
• Update: changes data, such as a student’s new address.
• Delete: removes old data that is no longer needed.
• Search: finds the data you ask for quickly.
• Secure: keeps data safe so only the right people can see it.

What is a table in a database?

A table is a grid of rows and columns in which a database stores data about one kind of thing.

• Looks like: a spreadsheet (Excel) grid.
• Difference from a spreadsheet: a table is stricter about how data is entered.
• Many tables: one database can hold several tables.

A “School Database” might have these tables:

• Students: details of every student.
• Teachers: details of every teacher.
• Subjects: the subjects taught in the school.

Splitting information into separate tables keeps the database neat and organised.

What are fields and records?

A field is a column that holds one kind of information, and a record is a row that holds all the information about one person or thing.

What is a field?

• Meaning: a single category of information, such as “First Name” or “Date of Birth”.
• Direction: runs vertically (up and down) as a column.
• Think of it as: a question the database asks about each person.

What is a record?

• Meaning: a complete set of information about one specific person or thing.
• Direction: runs horizontally (across the page) as a row.
• Think of it as: the answers for one person.

What is the difference between a field and a record?

What does a Students table look like?

The first row below holds the field names. Each row after it is one record.

• Fields: five columns (Admission No, First Name, Surname, Class, Date of Birth).
• Records: three rows, one for each student.
• Same name: records 2 and 3 share a name, but their admission numbers differ.

What is a primary key?

A primary key is a field whose value is different for every record, so it identifies each record uniquely.

Two students may have the same name, so the computer needs another way to tell them apart.

What are the rules of a primary key?

• Unique: no two records can have the same primary key.
• Not empty: every record must have a value in this field.
• Stable: the value should not change over time.

What are examples of a primary key?

• Admission Number: different for every student in a school.
• NIN (National Identification Number): different for every registered person.
• Student ID number: printed on a school ID card.

Which fields are not good primary keys?

• Name: two people can share the same name.
• Class: many students are in the same class.
• Date of birth: classmates can be born on the same day.

Key terms

Class activity

1. Design a table: If you were making a “Music Database”, what fields (columns) would you need? (For example, Song Title, Artist.)
2. Identify: Look at your school ID card. Which information on that card would be the primary key?
3. Discussion: Why is it better to store a phone number as a field than to write it in a long paragraph of text?

Evaluation

1. What is a database? Give two examples.
2. What is the job of a DBMS? Name two DBMS software packages.
3. State the difference between a field and a record.
4. Why do two students with the same name need a primary key?

Assignment

Design a “Students” table for your school. List at least five fields, say which field is the primary key, and write two sample records.