Data dictionary- A DBMS component that stores metadata - data about data.

• Thus, the data dictionary contains the data definition as well as their characteristics and relationships

System catalog- A detailed system data dictionary that describes all objects in a database

1:M relationship is the relational modeling ideal. Therefore, this relationship type should be the norm in any relational database design

1:1 relationship should be rare in any relational database design

M:N relationships cannot be implemented as such in the relational model

Index -An ordered array of index key values and row ID values (pointers). Indexes are used to speed up & facilitate data retrieval

Unique index -An index in which the index key can have only one associated pointer value (row)

Queries about this Lesson, please send them to: jmwaura@jkuat.ac.ke

*References*

• Database Systems: Design, Implementation, and Management, 12th ed. Carlos Coronel & Steven Morris
• Database Modeling and Design; Logical Design, 5th ed. Taby Teorey et.al
• Fundamentals of database systems, 6th ed. Ramez Elmasri & Shamkant B. Navathe