key field
In databases, a field used to uniquely identify a record or to establish relationships between tables.
このテーブルでは、社員番号がキーフィールドとして使われています。
In this table, the employee number is used as the key field.
Variant spelling with a middle dot, sometimes seen in technical writing.
Borrowed from English 'key field', a compound of 'key' and 'field'.