select last record in sub query - mysql

Question

have read all similar qs but cant apply to my sql
Would like to select all customers AND the last action record inserted.
The sql below first selects the max actionid then uses that on another sub query - this takes 5+secs to run ;(
Please advise TQ
SELECT cus.cusid,cus.FirstName,cus.Surname,
lastact.actionid, lastact.actiondate, lastact.siteid
FROM cus
LEFT JOIN(
SELECT MAX(actionid) AS maxactionid, cusid
FROM `action`
INNER JOIN `event` ON event.eventid = action.`eventid`
GROUP BY cusid
) AS maxactionid ON maxactionid.cusid = cus.cusid
LEFT JOIN (
SELECT
action.actionid,
action.actiondate,
event.cusid,
event.siteid
FROM
`action`
INNER JOIN `event`
ON event.eventid = action.eventid
ORDER BY actionid DESC
) AS lastact ON lastact.actionid = maxactionid
WHERE UCASE(CONCAT(firstname, surname)) LIKE '%JIM%HEMM%'
TQ for ideas - please see following:
1) the limit idea, provides null results for lastact.actionid, lastact.actiondate, lastact.siteid - but does run in 0.075 secs!
Such a shame this idea fails
SELECT cus.cusid,cus.FirstName,cus.Surname, lastact.actionid, lastact.actiondate, lastact.siteid
FROM cus
LEFT JOIN (SELECT action.actionid, action.actiondate, event.cusid, event.siteid
FROM action
INNER JOIN event ON event.eventid = action.eventid
ORDER BY actionid DESC LIMIT 1
) AS lastact ON lastact.cusid = cus.cusid
WHERE UCASE(CONCAT(firstname, surname)) LIKE '%JIM%HEMM%'
2) EXPLAIN results of original query are:
3) Adding LIKE 'JIM%' AND cus.surname LIKE 'HEMM%' doesn't affect query time much but will include as per suggestion
Hi - have got great result by using ideas from everyone - Thank you
1) Changed WHERE to cus.FirstName LIKE 'JIM%' AND cus.surname LIKE 'H%'
2) Added index on firstname, surname
3) Added cusid in action table (don't need event table anymore)
4) Moved lookup tables (not in orig question) outside of action sub query
Finished sql looks like (runs in 0.063 secs - tested with a surname of only one letter!)
SELECT cus.cusid,cus.FirstName,cus.Surname, lastact.actionid, lastact.actiondate, lastact.siteid, actiontype.action,
FROM cus
LEFT JOIN (
SELECT action.actionid, action.actiondate, event.cusid, event.siteid
FROM action
ORDER BY actionid DESC
) AS lastact ON lastact.cusid = cus.cusid
LEFT JOIN actiontype ON actiontype.actiontypeid = lastact.typeid
WHERE cus.FirstName LIKE 'JIM%' AND cus.surname LIKE 'H%'
GROUP BY lastact.cusid

Answer 1

As JC Sama said "change select MAX(actionid) by select actionid and adding a limit 1 and order by desc", helps indexed
searchs.
As David K-J said "run an EXPLAIN first to see what the planner is trying to do. I would suspect it's the (non-indexable) search on concatenation strings".
You shouldn't put jokers '%' at the begining of a string when comparing, that disables indexed search.
You shouldn't use functions when comparing (at least, avoid them if you can), also for the indexed search.
Now that you can use indexes, add them if you haven't done it yet.
I may be wrong here, but I don't see the point of the last LEFT JOIN, as far as I'm concerned. You could withdraw that data from the first LEFT JOIN. Neither why are you grouping by cusid.
With all, the sql I made is (obviously not tested, you may have to fix some thing):
SELECT cus.cusid,cus.FirstName,cus.Surname,
maxaction.actionid, maxaction.actiondate, maxaction.siteid
FROM cus
LEFT JOIN(
SELECT actionid AS maxaction, action.actiondate, event.cusid, event.siteid
FROM `action`
INNER JOIN `event` ON event.eventid = action.eventid
order by actionid desc limit 1
) AS maxaction ON maxaction.cusid = cus.cusid
WHERE cus.FirstName like 'JIM%' and cus.surname like 'HEMM%'