ISDD Unit

> Can cause unnecessary duplication It’s time consuming for the data operator to finish

A primary key is a field in a table that contains a piece of data that is unique for every record

A surrogate key is a field in a table which has been created by the system to ensure that a unique field exists for every record - a surrogate key is used instead of a primary key if no existing field is suitable.

A compound key is a primary key made up of two or more attributes to identify each record, row or instance.

A foreign key is a field in a table that is the primary key of another table.

> Saves time by reusing code Find errors quicker More organised Loads faster - for an entire website, all you need is one CSS file to be loaded.

> Inside a HTML tag Add a style tag to the head section Create a style sheet and add a link to the head

Metadata is data about data. For example, the file size and author of a sound file are examples of metadata. It is found in the head section of a webpage.

A static webpage is a webpage that does not change every time it is loaded, or if the user clicks on a button.

A dynamic webpage is a webpage that displays different content each time it is viewed.

Client-side validation is when the information that the user enters is checked by the user’s browser, possibly using a scripting language like JavaScript.

Server-side validation is when all the information is checked and verified by the server, not on the user’s computer.

A database driven website is one that pulls information from a database each time it is loaded.