Database Glossary – K
Useful Terms For Working With Data

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

K

Key

A key is a field, or combination of fields, that uniquely identifies a record in a table.

See also: Key, Primary.

Key, Candidate

1) One or more fields that will uniquely identify one record in a table.

2) A potential primary key.

Key, Composite

A key made up of two or more table columns that, together, guarantee uniqueness, when there is no single column available that can guarantee uniqueness by itself.

Key, Database

The unique value that exists for each record in a database. The value is often indexed.

Key, Foreign

A column or group of columns in a table that corresponds to or references a primary key in another table in the database. A foreign Key need not itself be unique, but must uniquely identify the field or fields in the table that the key references.

Key, Linking

A field value used to establish the link between a parent and a child table.

See also: Table, Child and Table, Parent.

Key, Primary

A field or combination of fields that uniquely identifies each record in a table, so that each record can be uniquely distinguished from every other occurring in the table. A table cannot have more than one primary key, and a primary key, by definition may not contain a null value.

Key, Secondary

A key that is not the primary key for a table.