Now that you are familiar with the basics of PHP, you can begin looking at integrating a database into your scripts. As you might recall, Chapter 2, “Storing and Retrieving Data,” described the advantages of using a relational database instead of a flat file. They include
RDBMSs can provide faster access to data than flat files.
RDBMSs can be easily queried to extract sets of data that fit certain criteria.
RDBMSs have built-in mechanisms for dealing with concurrent access so that you, as a programmer, don't have to worry about it.
RDBMSs provide random access to your data.
RDBMSs have built-in privilege systems.
For some concrete examples, using a relational database allows you to quickly and easily answer queries ...