Microsoft Access is a general purpose database manager that can organize and manipulate any data that can be expressed in tabular form.

Users with a basic understanding of relational database management will find Microsoft Access to be powerful and easy to use. Hopefully, the sample application soon to be developed will give those who have not seen the inner workings of relational databases some insight into how they work.

In addition to accessing popular desktop database file formats, Microsoft Access can be used to build "front end" applications that tap the data stored on remote servers in several formats via Microsoft's Open DataBase Connectivity (ODBC).

Access97 is Internet and Hypertext Markup Language (HTML) enabled. The help file lists several documents on this topic. You can export a table, query, form, or report to HTML format.

The desktop database files can be imported into the Microsoft Access and converted to a native table in the Microsoft DataBase file (MDB). If others not using Microsoft Access or different versions share the data then the data can be linked to your Microsoft Access application without conversion. The data may be updated using other database managers and other "front end" applications.

In this context a database includes all of the related data tables, the queries that filter and relate the data in the tables, the forms, the reports, and any programming that has been done to automate the application. All of these objects are stored in one database file with an MDB extension.

In the case of tables that are linked, and not imported or created in the application, the MDB file would include everything except the data, which would remain in the original location. Your application would update the data in place on your server or other location.

You can use Microsoft Access interactively with no programming at all, but to get the most out of the program you will want to build applications that tap into some of the power available.

Microsoft Access includes four facilities to customize and automate an application. 1. Query By Example (QBE) queries build Standard Query Language (SQL) statements that filter and relate your data. (SQL is behind the scenes, but available, and the user does not have to deal with it at all if they prefer not to.) 2. Property sheets are used in table creation and on forms and reports to format and tie things together. 3. Macros are simple programming bits that are accomplished by pointing and clicking your way through a series of drop down lists. And 4. Visual BASIC for Applications programming language is used for tasks that are unavailable with the simpler methods.

For example, if you want to automate entry of today's date in a field on a data entry form, construct a macro, name it, save it, then use the property sheet of the target field to call the macro.

Microsoft Access is as modern as any database manager. You build applications using event driven, visual programming techniques. To build a form use a "wizard" to help, then use the form as is or modify it to suit your needs and tastes, or start from scratch and drag and drop all of the elements that are needed to make it work.

I have found Microsoft Access to be very forgiving when you change your mind about something. You can build your application "on the fly" and modify nearly anything after you have started. About the only things you can not do without losing data is to shorten the length of a data field or change the data type of a numeric or date/time field. You could lose the data in the field in question, depending on what you did to it.

You can add graphics to make forms and reports more attractive or meaningful. Command buttons can give yourusers access to your automation programming.

Just about any kind of data can be included in a Microsoft Access database. When creating or modifying the table structure simply select one of the following from drop down lists:

You can enter field validation rules in the table design window. Input masks e.g. to format phone numbers, can be added to the table design or to your data entry form or both. Data entry forms can include drop down lists or combo boxes to limit the field entry to only those approved such a list of approved vendors.

If your data already exists somewhere you can import or link the tables. The following list includes file formats that you can import:

The Microsoft Access tables save disk space by using variable length records. Most database files employ fixed length records. In a fixed length record file, if a field is empty, the empty space is stored in the file. If a 255-character text field contains only 10 characters space for all 255 characters are stored in that field in EVERY record in the file.

Another advantage of the MDB format is that you don't create lots of little files for your application. Your data and auxiliary files are all bound together in one file. No disk space wasted by cluster size. (Refer to my "This & That" column on cluster sizes.) You can easily do a backup of your Microsoft Access database, there's only one file to keep track of. You can keep it in the same directory with other data without getting confused about what belongs to what.

Microsoft Access improves with each new version, now 97. First there was 1.0 then 1.1, then 2.0, then 7.0, now Microsoft Access97. It is still a work in progress, which is good for the user. But each new version has used a new data file format making it impossible for users of older versions to share the files created or updated by the later versions. BE AWARE that older versions cannot read the data files created or converted by the newer versions. And it has been written that Microsoft Access 2.0 running on 16-bit Windows 3.1 cannot read data files saved by Microsoft Access 2.0 running on 32-bit Windows 95 or NT!

If you have to share your Access files between 16-bit and 32-bit Windows, it looks as if you'll have to either work on the 16-bit version first then convert it to 32-bit, or work on each separately.

To prevent entering data twice, you may want to link your data files to the application rather than have them contained in the same file as your application. You can create dBASE files with quite a few applications including most popular spreadsheet programs. (Do use dBASE IV or V format if you have the choice because the indexes are automatically maintained in one file for you.) Then link them to your application by following the instructions in Microsoft Access .

Incidently, with Version 7.0 the Microsoft Access programming language is Visual BASIC for Applications. This means that you use the same syntax and key words as in programming in Microsoft Excel or Word. This will be a big help to those programming for all the Microsoft Office applications.

We will build a sample application.