Among the patients who has a normal anti-scl70, how many of them are male and have the symptom of vertigo?
normal anti-scl70 refers to SC170 IN('-', '+-'); male refers to Sex = 'M'; symptom of vertigo refers to symptoms = 'vertigo'; Should compute the number of distinct ones
SELECT COUNT(DISTINCT T1.ID) FROM Patient AS T1 INNER JOIN Laboratory AS T2 ON T1.ID = T2.ID INNER JOIN Examination AS T3 ON T3.ID = T2.ID WHERE (T2.SC170 = '-' OR T2.SC170 = '+-') AND T1.SEX = 'M' AND T3.Symptoms = 'vertigo'