Databases: 3 Common Mistakes – Grade 12 ITGS revision

Don't confuse spreadsheets (above) with databases

Databases are extremely common in IT systems and as such, the likelihood of an exam question involving them is extremely high. Here are three misunderstandings I find students often have:

Spreadsheets versus Databases

Students sometimes confuse these types of application programs. Spreadsheets are used when the primary function is calculations based on data – such as calculating student grades, budgets, or costs. Examples of spreadsheets inclue Microsoft Excel, LibreOffice Calc, and Apple’s Numbers.

Databases are used to store data in an organised way and retrieve it later. They are useful for storing a large amount of information and retrieving subsets of it. For example, a school database contains students records and we can retrieve a list of all students in grade 12, or all of those who have a low attendance rate. Many businesses use databases, most e-commerce sites (e.g. Amazon) are backed by databases containing product details, and specialist databases power sites like Facebook and Wikipedia. Examples of database programs include Microsoft Access, LibreOffice Base, MySQL, and SQLServer.

Telephone number fields should be text

If a telephone number is stored as numeric data, any leading zeroes will be chopped off, and it will not be possible to enter special symbols such as plus signs or brackets (though these are not technically needed). Because of this, the data type of telephone number fields should be text.

Databases should not store a person’s age

Storing a person’s age in a database causes two big problems: firstly, the age will need updating every year, and secondly, we won’t known WHEN to update the age. These cause data integrity problems. Instead of storing age, a database should store a person’s date of birth. A simple calculated field can then work out the person’s age based on the current date.

You can see page 143 for more information about databases and page 194 for spreadsheets.

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