Charles asks you, “What is an entity, a table, a field, and a record?” He also wants to know the different between primary key, candidate keys, foreign keys, secondary keys, and combination keys.

What will be an ideal response?

You might explain to Charles that an entity is a person, place, thing, or event for which data is collected and maintained. A table contains a set of related records that store data about a specific entity. A field is a single characteristic or fact about an entity. A record is a set of related fields that describes one instance, or occurrence of an entity, such as one customer, one order, or one product. A primary key is a field or combination of fields that uniquely and minimally identifies a particular member of an entity. A candidate key is any field that could serve as a primary key because sometimes you have a choice of fields or field combinations to use as the primary key. A foreign key is a field in one table that must match a primary key value in another table in order to establish the relationship between the two tables. A secondary key is a field or combination of fields that can be used to access or retrieve records.