How many patients have a normal anti-SSB and are diagnosed with SLE in the examination?
normal anti-SSB refers to SSB IN('-', '+-'); '-' is expressed as 'negative' and '+-' is expressed as '0' in the database ; diagnosed with SLE refers to Diagnosis = 'SLE'; 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 WHERE T2.SSB = 'negative' OR '0' AND T1.Diagnosis = 'SLE'