Final answer:
In an ER diagram, a foreign key is indicated by a line connecting the primary key of one entity to the corresponding attribute of another, with a 'crow's foot' symbol at the end of the child entity.
Step-by-step explanation:
In an Entity-Relationship (ER) diagram, a foreign key is denoted by drawing a line between the relevant entities. The line typically connects the primary key attribute of one entity (the parent entity or referenced table) to the attribute of another entity (the child entity or referring table) that will hold the foreign key.
The line should have a crow's foot at the end that touches the entity that has the foreign key (the many side of the relationship), while a single line (denoting 'one') is at the end of the entity containing the primary key referenced by the foreign key.
An arrow or a specific notation such as '' can be used to indicate the direction of the relationship and to clarify which field is the foreign key. Moreover, some variations of ER diagrams might use different notations or symbols, so it is essential to be familiar with the notation system used in your specific course or documentation.
Steps to denote a foreign key in an ER diagram:
Identify the entities (tables) that will have the relationship.
Determine which entity has the primary key that will be referenced elsewhere.
Draw a line between the two entities to represent the relationship.
End the line with a 'crow's foot' at the side of the entity that contains the foreign key.
Optionally, label the foreign key with '' to make it clear.