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Yet, despite how common databases are, they aren't very well understood.<br />
Every day, new webmasters become database administrators without even<br />
understanding the first thing about databases. When you use a database on<br />
the web today, you're not just using any database: you're using ones that<br />
rely on concepts built up over decades of database development and proven<br />
effective. Here are some of those concepts.<br />
Relational Databases.<br />
The most common database model in use today is that of the relational<br />
database – others include hierarchical databases (where data is organised in<br />
'trees', like an organization's management structure), and flat file databases<br />
(where data is stored in 'records' in a text document).<br />
In a relational database, data is stored in tables. The columns are called<br />
fields and the rows are called records. So, for example, a table might have<br />
two fields: firstname and lastname. If you then added a record to this table,<br />
it could be 'Bob' and 'Smith'. Instead of just having that data, you have<br />
labeled it with what it is, and that lets you refer to it and search through it<br />
much more easily.<br />
Where the 'relational' part is really significant, though, is when it comes to<br />
the way tables in a database relate to the other tables. Each record of each<br />
table has an ID number (technically known as the 'primary key') – for<br />
example, the Bob Smith record might be ID number 123. This then lets you<br />
refer to his record in a new table.<br />
Let's say you were storing records of people's orders. You could have two<br />
columns: customer number and date. This lets you simply store 123 and the<br />
date in the table each time Bob Smith orders from you – the relational<br />
nature of the database will tell you later on that customer number 123 is<br />
Bob Smith. When it comes to things like, for example, storing posts made by<br />
multiple authors, this is powerful.<br />
SQL Databases.<br />
SQL stands for 'Structured Query Language'. It's the most popular language<br />
for making queries to relational database systems. What's a query? It's<br />
basically a way of asking the database to find a record for you that matches<br />
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