At the core of any web based or enterprise application lays the database, where the data, content, and configuration of an application are stored. Modern database management systems, or DBMSs, are extremely powerful and good and quickly parsing a query and executing it in the fastest method possible. Some databases are capable of directly storing objects and xml structures and querying them using a powerful extension to the SQL query language.
The two main types of database designs are DSS (Decision Support System) and OLTP (On-line Transactional Processing). DSS based database designs are geared towards historical data and business intelligence. This data is updated infrequently, however reports and queries are constantly being run against these tables so indexing and minimization of query overhead is an important factor. OLTP databases, however, are usually found in LOB (line of business) applications and are constantly updating and inserting new records. Reports and queries may still be performed against the tables found here, however the data is not the same magnitude as that of DSS databases and is usually much more normalized to provide the best efficiency and data integrity.