Database services under Linux that use the software discussed in this chapter are based on a client/server model. Database clients are often used to input data and to query or display query results from the server. You can use the command line or a graphical client to access a running server. Databases generally come in two forms: flat file and relational. A flat file database can be as simple as a text file with a space, tab, or some other character delimiting different parts of the information. One example of a simple flat file database is the
/etc/passwd file. Another example is a simple address book that might look something like this:
Doe~John~505 Some Street~Anytown~NY~12345~555-555-1212
You can use standard ...