The existential quantifier (∃) implies “there exists” or “at least one.” Thus, ∃t ∈ Students (t.Age = 18) correctly represents that there exists at least one student in the set Students whose age is 18. This query will return true if there is at least one student who is exactly 18 years old in the set of tuples representing students and their ages.
∃t ∈ Students (age > 30) employ the existential quantifier “∃” to verify if there is a tuple t in the set of students over 30. Because students’ ages are frequently less than 30 (assuming a regular student age range), this query may not return true unless there is an anomaly or incorrect data.