A table can have only one of the following constraints, which one? code example
Example: how to permit only a few values in dbms
ALTER TABLE [TableName] ADD CONSTRAINT
my_constraint CHECK (PatientType = 'Admitted' OR PatientType = 'OPD')
ALTER TABLE [TableName] ADD CONSTRAINT
my_constraint CHECK (PatientType = 'Admitted' OR PatientType = 'OPD')