Flat File Database - Example Database

Example Database

The following example illustrates the basic elements of a flat-file database. The data arrangement consists of a series of columns and rows organized into a tabular format. This specific example uses only one table.

The columns include: name (a person's name, second column); team (the name of an athletic team supported by the person, third column); and a numeric unique ID, (used to uniquely identify records, first column).

Here is an example textual representation of the described data:

id name team 1 Amy Blues 2 Bob Reds 3 Chuck Blues 4 Dick Blues 5 Ethel Reds 6 Fred Blues 7 Gilly Blues 8 Hank Reds

This type of data representation is quite standard for a flat-file database, although there are some additional considerations that are not readily apparent from the text:

• Data types: each column in a database table such as the one above is ordinarily restricted to a specific data type. Such restrictions are usually established by convention, but not formally indicated unless the data is transferred to a relational database system.
• Separated columns: In the above example, individual columns are separated using whitespace characters. This is also called indentation or "fixed-width" data formatting. Another common convention is to separate columns using one or more delimiter characters. There are many different conventions for depicting data such as that above in text. (See e.g., Comma-separated values, Delimiter-separated values, Markup language, Programming language). Using delimiters incurs some overhead in locating them every time they are processed (unlike fixed-width formatting) which may have some performance implications. However, use of character delimiters (especially commas) is also a crude form of data compression which may assist overall performance by reducing data volumes - especially for data transmission purposes. Use of character delimiters which include a length component (Declarative notation) is comparatively rare but vastly reduces the overhead associated with locating the extent of each field.
• Relational algebra: Each row or record in the above table meets the standard definition of a tuple under relational algebra (the above example depicts a series of 3-tuples). Additionally, the first row specifies the field names that are associated with the values of each row.
• Database management system: Since the formal operations possible with a text file are usually more limited than desired, the text in the above example would ordinarily represent an intermediary state of the data prior to being transferred into a database management system.