(单选题)23: Given the tables:
COUNTRY STAFF
id name person cities id name
1 Argentina 1 10 1 Aaron
2 Canada 2 20 2 Adams
3 Cuba 2 10 3 Jones
4 Germany 1 0
5 France 3 5
6 Italy 1 5
the report:
id name number_of_countries
---------- ---------- -------------------
1 Aaron 3
and the SQL statement:
SELECT B.id,B.name,COUNT(DISTINCT A.name) AS number_of_countries
FROM country A, staff B
WHERE B.id=A.person
GROUP BY B.id,B.name
HAVING COUNT(DISTINCT A.name)>:count_var
Which of the following values does :count_var require to print out the above
report?
A: 1
B: 2
C: 3
D: 4
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