Spreadsheet vs Database When do we use them?

Spreadsheet review Why do we use a spreadsheet?

Spreadsheet review Enter data Do calculations on data Examples: expenses, profit/loss

Expenses

Gradesheet

Database Store information long-term Search information

An example… What sort of information does Ren Da Fu Zhong need to keep? Think of at least 10 pieces of information!

RDFZ stores information on… Students: –Name, address, ID number, parents, grades, classes, teachers, payment info, absences, extra activities Teachers: –Name, address, ID number, classes taught, students taught, grades given, bank information, payment information

RDFZ stores information on… Other employees: –Name, job, hours worked/week, pay scale, bank information, duties/responsibilities Inventories: –How many classrooms, how many desks, chairs, overhead projectors, scanners, computers…

RDFZ stores information on… Lots of stuff! Can all of this fit on one spreadsheet? –No! –This is when we use a database.

Uses of a database Store data Backup data Add/Modify data Query data (ask questions) Generate reports (print data in an easy-to- read format)

Examples of databases Can you think of any?

Your music

Your games

Your web pages

Your life

Warning! Databases are very different from word processors, spreadsheets, or presentation software. You CANNOT just start typing. A database must be DESIGNED before you start adding data. Why?

Avoid duplication (putting in the same data many times) Logical organization of data

The parts of a database Do you remember: –Columns? –Rows? –Cells? These have different names in a database… 

Table: one page

Column = Field We have 3 fields: ID, title, and date Notice – every field has the same data type! This is required!

Data Type review Remember these from Excel?

Row = Record Here we have 4 records Each record has all the information from one entry.

Another example Here we have 3 records A record has all the info on one entry

Cell: Data Value How many data values are in this table?

Primary Key Here, the “Video Collection” field is the primary key EVERY table MUST have a primary key – a unique value

Primary Key Examples

Designing a Database Before we enter data, we must design the table Things to think about: –What fields do we need? –What data type does each field need? –Which field can become the primary key?

Example: RDFZ What information will RDFZ store about students? What data type should each be? Which field will make a good primary key?

Example: Taobao business We are running a business on TaoBao. We are selling clothing on the internet. We want to make a database of all the orders that we receive. What information must we store? What data type should each field be? What should be the primary key?

Example: a new home We are real estate agents, and need to build a database of all apartments in the area. What information must we store? What data type should each field be? What should be the primary key?