Application software: Database applications

Database applications

Databases are useful at both the managerial and clerical levels in an organization. At the managerial level they are a decision-support tool, for reports can be produced from them which summarize what's going on and give pointers for the future. At the clerical level they provide an easy way of entering and retrieving data, and dealing with enquiries.

So in many situations a clerk will require access to a database to carry out the latter type of task, and a manager will require access to it to get out a report. Where personal computers are used, this may mean two or three people having access to the same PC, or else setting up a configu­ ration of multiuser or networked PCs.

Some database applications are almost exclusively 'cleri­cal', an example being a name-and-address file. Most data­ base applications, though, have both clerical and managerial elements.

Typical business database applications include:

• Stock records.

• Personnel records.

• Customer records.

• Accounts.

• Mailing lists.

Spreadsheet software

A spreadsheet is a software package which organizes data in the form of a table or worksheet. An example of a worksheet is shown in Figure 6.3. This is a simple cash-flow forecast for a small business. As you can see from this example, it is mainly with numbers, and calculations on numbers, that spreadsheets are concerned.

In this worksheet, if you alter any of the income or expenditure data, the computer immediately and automati­cally recalculates the cash-flow forecast on the bottom lines.

As anyone who has had anything to do with cash-flow forecasts will testify, this is much better than having to do the job manually.

Spreadsheets have some similarities with the record­ keeping packages described in the last chapter, and you can think of a worksheet as a file of records listed in tabular form:

• Each column in a worksheet corresponds to a field in a record.

• Each row corresponds to a record.

• Programming statements can be inserted so that calculations are carried out automatically.

(You can, in fact, import a set of records prepared on a database package such as Q&A into a spreadsheet package such as Lotus 1-2-3. When you do so, the records will be listed in worksheet form. Or you can import a Lotus worksheet into a database package such as Q&A, and each row becomes a separate record.)

Spreadsheet concepts

Spreadsheets share a number of concepts with record­ keeping packages, including the concepts of file, data, label, and template. Concepts that are special to spreadsheets, which are dealt with below, are column, row, cell, formula, and window.

Column. A worksheet is split vertically into columns, which can correspond to the fields in a database. The default column width is normally 9 characters, though this can easily be altered either globally (i.e. across the entire worksheet) or for individual columns. Most spreadsheet packages will cope with worksheets running into hundreds of columns, though the number you can actually use depends upon the amount of RAM in your computer.

Columns are normally identified by letters, starting A, B, C, ... , and continuing through AA, AB, AC, ... , BA, BB, BC, and so on. To make the worksheets you design easy to read, you should label each column by typing a heading at the top. In Figure 6.3, the column labels are the months of the year.

Row. A worksheet is also split into rows, i.e. horizontal lines of data which can correspond to the records in a database. Rows are numbered downwards, starting at 1. Most spreadsheet packages will, in theory, permit work­ sheets extending to several thousand rows, though in prac­ tice the number you can use depends on your computer's RAM. To make your worksheet design easy to read, you should normally type in row labels at the left, as is done in Figure 6.3.

Cell. A cell is the space occupied by an individual item of data in a worksheet. It is identified by the column letter and row number in which it lies. For example, the cell lying at the intersection of column C and row 4 is called C4.

Formula. Besides data, a cell can contain a programming statement, or formula. These are not visible when you are entering data, but they reside in the background. A formula normally involves a mathematical calculation on the con­ tents of other cells, the result being inserted in the cell which contains it.

Window. Most business worksheets are quite large, extending beyond the edges of the computer screen. The screen is, in effect, a 'window' into the worksheet. Many spreadsheet packages allow you to set up two or more windows onto your worksheet, so that two or more parts of it can be displayed at the same time on the screen.