CREATE TABLE demographic (subject_id CLOB, hadm_id CLOB, name CLOB, marital_status CLOB, age CLOB, dob CLOB, gender CLOB, language CLOB, religion CLOB, admission_type CLOB, days_stay CLOB, insurance CLOB, ethnicity CLOB, expire_flag CLOB, admission_location CLOB, discharge_location CLOB, diagnosis CLOB, dod CLOB, dob_year CLOB, dod_year CLOB, admittime CLOB, dischtime CLOB, admityear CLOB)
CREATE TABLE procedures (subject_id CLOB, hadm_id CLOB, icd9_code CLOB, short_title CLOB, long_title CLOB)
CREATE TABLE prescriptions (subject_id CLOB, hadm_id CLOB, icustay_id CLOB, drug_type CLOB, drug CLOB, formulary_drug_cd CLOB, route CLOB, drug_dose CLOB)
CREATE TABLE lab (subject_id CLOB, hadm_id CLOB, itemid CLOB, charttime CLOB, flag CLOB, value_unit CLOB, label CLOB, fluid CLOB)
CREATE TABLE diagnoses (subject_id CLOB, hadm_id CLOB, icd9_code CLOB, short_title CLOB, long_title CLOB)

tell me the number of patients who had pt lab test and are less than 59 years of age.
SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE demographic.age < "59" AND lab.label = "PT"
SELECT COUNT(DISTINCT "demographic"."subject_id") FROM "demographic" JOIN "lab" ON "PT" = "lab"."label" AND "demographic"."hadm_id" = "lab"."hadm_id" WHERE "59" > "demographic"."age"