instruction: what is the number of patients whose diagnoses short title is malnutrition mild degree and lab test fluid is urine?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE diagnoses.short_title = "Malnutrition mild degree" AND lab.fluid = "Urine"