oracle10g - How to create trigger that will run a subquery to count data -



oracle10g - How to create trigger that will run a subquery to count data -

i have appointment table patient_id. want, patient can create maximum 3 appointment. want trigger check total appointment made patient using patient_id before insert data. trigger raise error if count > 3.

can tell me how can that?

thanks

triggers oracle10g constraints

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