Slow query performance in MySQL - mysql

Question

I would like to find out what causes the slow execution of my MySQL query here. It's 1 row fetched in 0.0017s (3.6215s) How can i optimize this?
SELECT hadmlog.hpercode as 'HOSPITAL NUMBER', FLOOR (hadmlog.patage) as 'AGE', CONCAT (hperson.patlast, ', ', hperson.patfirst, ' ',hperson.patmiddle) as 'PROFILE', hcity.ctyname as 'DISTRICT', hadmlog.disdate as 'DISCHARGED DATE'
FROM hadmlog
INNER JOIN hperson ON hadmlog.hpercode=hperson.hpercode
INNER JOIN haddr ON hadmlog.hpercode=haddr.hpercode
INNER JOIN hcity ON haddr.ctycode=hcity.ctycode
WHERE hadmlog.patage BETWEEN '1' AND '4'
AND hperson.patsex = 'M'
AND DATE(hadmlog.disdate) = DATE(curdate())
AND haddr.haddrdte = ( select max(haddrdte)
from haddr
where haddr.hpercode = hperson.hpercode )
ORDER BY Profile;

Answer 1

First, fix the query:
SELECT al.hpercode as HOSPITAL_NUMBER, FLOOR(al.patage) as AGE,
CONCAT_WS(' ', p.patlast, p.patfirst, p.patmiddle) as PROFILE,
c.ctyname as DISTRICT, al.disdate as DISCHARGED_DATE
FROM hadmlog al JOIN
hperson p
ON al.hpercode = p.hpercode JOIN
haddr a
ON al.hpercode = a.hpercode JOIN
hcity c
ON a.ctycode = c.ctycode
WHERE al.patage BETWEEN 1 AND 4 AND
p.patsex = 'M' AND
al.disdate >= curdate() AND
al.disdate < curdate() + INTERVAL 1 day AND
a.haddrdte = (select max(h2.haddrdte)
from haddr h2
where h2.hpercode = p.hpercode
)
ORDER BY Profile;
Some of the changes are cosmetic (such as the table aliases and CONCAT_WS()). The more relevant changes are:
patage appears to be a number, so make the comparisons numbers. Strings can impede the optimizer.
date(disdate) can also impede the optimizer.
Then, for this query, I am guessing that you want an indexes:
hadmlog(disdate, patage)
And then you want indexes on the JOIN keys used for the other tables.