Foreign Keys was created in 1985.
A spurious tuple is a record in database that get created when two tables are joined badly. Spurious tuples are created when two tables are joined on attributes that are neither primary keys nor foreign keys. Hopes this will help you .
Yes Foreign key can have null value.
Tables, Entities, Attributes, Primary Keys, and Foreign Keys
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The Bo-Keys was created in 1998.
The Mar-Keys was created in 1958.
The Keys to the Street was created in 1996.
The Black Keys was created in 2001.
Keys to Imagination was created in 1986.
The Keys to Maramon was created in 1990.
The Keys of This Blood was created in 1990.
Frederick Keys was created in 1989.