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Is there a specific term to describe a relation with a cardinality of one?

I'm thinking particularly of RDBMS "special" one-row tables, for example, DUAL (Oracle), SYSIBM.SYSDUMMY1 (DB2, Derby) and RDB$DATABASE (Interbase, Firebird).

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    Interesting question, I've come across these in some vendor databases, usually "settings" tables – Ben Brocka Dec 13 '11 at 20:43
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Singleton Table. In relational terms it is a relation with primary key ∅ (the empty set).

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    +1 A colleague suggested this moniker, too. (He also suggested "highlander table," which has a certain charm.) – pilcrow Dec 13 '11 at 20:02
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    That's a singleton table, too. – miracle173 Sep 2 '14 at 16:47

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