Enforcement of 1 to many

Gurus,

I need to enforce a 1 ( mandatory ) to many relationship between 2 tables. Can the database do this or should we control it at the application level ? We do have a FK on the child table but how do we enforce ALL parents to have at least 1 child ? Procedurally ?

TIA,
Cliff
( I have 2 kids so I'm covered )

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