Keywords: Entity Relationship Diagram.jpg Entity relationship ER diagram<br> A design tool that graphically expresses the database ™s overall logical structure by representing data entities their cardinality relationships e g one-to-one one-to-many etc and the linkages that connect them The construction of an ER diagram is essential for the design of database tables extracts and metadata see definition of metadata ER diagrams are especially important in designing and developing data documentation and tables that represent data relationships see data/process flow diagram and data structure diagram http //knowledge fhwa dot gov/tam/aashto nsf/All+Documents/4825476B2B5C687285256B1F00544258/ FILE/DIGloss pdf Data Integration Glossary 2001-08 U S Department of Transportation PD-USGov Data dictionary Entity-relationship models |