Firstly, what exactly is a database? Well, a database is an organised collection of information. It might simply be a list of names and addresses whether they be customers, members of your family or friends. In addition you might record their birthdays, phone number etc. It could be employee payroll information, your library of books, music or videos, details of what software you have. The amount of information could be small or large.
The information (data) is split into categories called fields. For example, with a list of names and addresses you would have the last name, first name, title (Mr, Mrs, Miss, Dr etc), post or zip code, town or city, county or state, street address. The last might be split down into two parts to take account of housenames etc. The collection of fields describes the data. So, we have now given our fields names. These are usually arranged in a row. Each row of data is called a record. In our example each record would describe one person.
The data can be organised virtually how you want. In other words you can sort the data according to various criteria. For instance, you might sort by last name. This would arrange the last names A-Z if in ascending order or Z-A if in descending order since A is the start of the alphabet.
| Ant | Adam | Wigan |
| Aster | Gay | Chester |
| Burrows | Paul | London |
| Hill | Harry | Taunton |
Additional criteria can be used. For instance, we could sort firstly by last name and then by town. This would mean that if there were two people with the same last name the one who lives in the town that has the first first letter would appear above the other. If we had two Hills then the one in Chester would appear above the one in London.
Record 1 in the above example describes Adam Ant, record 2 describes Gay Aster. The way the data is presented above is in the form of a table. Data can be entered directly into the rows of the table. But it is often more convenient to enter the data into a pre-designed form. This has the advantage that different files or tables can be used for different purposes. For instance, one table might describe film directors, another the films themselves.
Data can be input in any order. For instance, the Smiths could be done before the Hills. This is all very well, but the data is then unordered. It is not in any particular order. Not only that, we might only want a part of that data. This is where sorting comes in. However, we can also use tools to query the database and extract the information we require. Suppose you have a database of cars. You could query the database to extract all cars made by one manufacturer or all cars above a certain engine size or all those with only two doors. Or any combination. Provided the fields exist and the information is in the database.
It is important then to think carefully about the design of the database. There could be a lot of work involved if you change your mind later! We shall be looking in more detail at database design later.
Often we want to commit the data we have extracted to paper. In order to get it to fit exactly how we want and only include the fields that we want we have to design a report. A report allows flexibility besides being versatile.