Download PDF Abstract In the process of designing various electric power facilities, the design engineer processes a large amount of information. It includes technical parameters of equipment (types, capacities, ratings, dimensions, classes of protection and fire safety, etc.), normative and technical documentation (State Standards, Construction Standards and Regulations, etc.), which in one way or another directly influence the final result of the project. In addition to searching for and processing this information, the designer uses it to select and calculate various options. The engineer is heavily overloaded with information, which often leads to errors and inaccuracies in the development of the project. All this together makes it necessary to develop CAD to facilitate the work of the designer. In the construction of CAD, one of the main and integral stages is the development of a database, which is a set of data stored in a computer that meets the information needs of computer-aided design with minimal redundancy and maximum possible speed, thereby relieving the designer of lengthy searches for information. However, creating a database does not mean just collecting a large amount of information in one place. In order to work together with CAD, a schema is formed, which is represented by a logical structure for creating and maintaining a database. A schema is a set of rules, which organize information, create logical and functional relationships and implement relationships between database objects. This paper discusses the process of developing a database for CAD "closed switchgear CAD". The basis for the database is a widespread and easy-to-learn Microsoft SQL Server platform. The basic principles of building links in this database with examples are considered. Keywords SQL, database, designing, electrical engineering, CAD, algorithm, software, development, substation, automation.