SELECT
COALESCE(b.provcode,'None') AS "Primary Prov",
a.lastname,
a.firstname,
a.ID,
DATEDIFF(year,DOB,intakedate) AS "AgeAtIntake",
DATEDIFF(year,DOB,current date) AS "AgeNow"
FROM
patients a
JOIN providers b ON a.providernum = b.providernum
WHERE
flag = 0   //active patient
AND dischargedate IS NULL   //no discharge date has been entered
AND AgeAtIntake < 18    
AND AgeNow >= 18
ORDER BY "Primary Prov", a.lastname, a.firstname, a.id