Microsoft SQL Server 2005 Compact Edition (SQL Server Compact Edition) is designed for developers who need light weight, in process relational database solution for their applications that can be developed and deployed on desktop as well as on mobile devices. SQL Server Compact Edition Runtime can be used to develop and deploy applications on desktop.
SQL Server Compact Edition is a powerful, yet lightweight relational database engine that makes it easy to develop desktop applications by supporting familiar Structured Query Language (SQL) syntax and providing a development model and API consistent with SQL Server. When compared to its previous release, SQL Server Mobile, SQL Server Compact Edition includes new features like |DataDirectory| and ClickOnce support for ease of deployment (Please see SQL Server Compact Edition Readme)
Microsoft, SQL Server 2005, Compact Edition