foreign key

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foreign key

A column in a database table containing values that are also found in some primary key column (of a different table). By extension, any reference to entities of a different type.

Some RDBMSs allow a column to be explicitly labelled as a foreign key and only allow values to be inserted if they already exist in the relevant primary key column.

[Is it still a foregn key if the primary key is in a different column in the _same_ table?]

(2005-01-14)