Supporting domain-specific functions and relieving users from the database details are two major challenges faced by many today's database applications, especially in life science research. The most commonly used workaround is the form-based query interface. However, it has severe limitations on expressive ability, extensibility, and flexibility. Unlike most of previous studies that adopted domain-specific query strategies, this book proposes a conceptual query methodology that can be generally applied in any domain. Meanwhile, it allows data-users to define their own domain-specific query functions. It is independent of database management systems and can be integrated into already-released systems as a complemental query function. This book will be of interest to biologists who are looking for a novel query methodology, to bio-database creators who are developing biological database applications, and to existing database system administrators who would like to provide a complemental query function for end-users.