This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
A Database is primarily used for record. Like application databases which work as Online Transaction Processing System where in every transaction has to be recorded, and it is highly optimized for write operations to make sure that every transaction gets recorded. The tables and joins in tables are complex as they are normalized to save storage space. A database uses Entity Relationship model for design.
A Data Warehouse is also a kind of database which is designed to speed up the process of querying and analysis. These databases are read optimized. A data warehouse works as Online Analytical Processing System where in tables and joins are highly de normalized to reduce the response time of queries. It uses data modeling techniques for design and is primarily used to maintain historical data to aid in taking quality business decisions.