How to get latest date from SQL table - sql

Question

So I have two tables:
workersTbl (workerName and workerID)
workersLogTbl (workerID and workerLogTime)
e.g. workerTbl: workerName = John Smith | workerID = 5
When you pull the workerLogTbl (i.e.
SELECT * FROM workerLogTbl where workerID = 5
This should give you multiple times the worker logged in.
How do I pull all the workers names and also pull the latest log in time (supposing I join the two tables using workerID)?
Thanks.

Answer 1

you can try:
select l.*
from workerlogtbl l
inner join workerstbl w on l.workerid = w.workerid
where l.workerid = 5
order by l.workerlogtime desc
what i have done is join the two tables together with the common fields from both tables and then ordered by the workerlogtime in descending order. if you need more info on joins take a look here

Answer 2

What have you tried so far? Try adding a GROUP BY w.workerId clause and adding aggregate function in the SELECT list, MAX(t.workerLogTime). –
SELECT w.workerId
, MAX(t.workerLogTime) AS latest_time
FROM worker w
LEFT
JOIN workerLogTbl t
ON t.workerId = w.workerId
GROUP BY w.workerId
ORDER BY w.worderId

Answer 3

The first way is to use an inner join, which assumes every worker you are interested in has an entry in the workersLogTbl
SELECT w.workerName, max(wl.workerLogTime) as LastLogTime
FROM workersTbl w
INNER JOIN workersLogTbl tl on (w.workerId = wl.workerId)
WHERE (w.workerId = 5)
GROUP BY w.workerName
A second way uses an outer join. This is useful to capture those workers who do not have an entry in the workersLogTbl. Note that if there is no corresponding entry in workersLogTbl then LastLogTime will be null.
SELECT w.workerName, max(wl.workerLogTime) as LastLogTime
FROM workersTbl w
LEFT OUTER JOIN workersLogTbl tl on (w.workerId = wl.workerId)
WHERE (w.workerId = 5)
GROUP BY w.workerName
note that the outer word isn't generally necessary: left join is normally sufficient.
A third way is to use a subquery. This is useful if you are also wanting to get other aggregate results in the same query. Such as if we wanted the first and last log time for the worker, for example:
SELECT w.workerName,
(SELECT MAX(wl.workerLogTime) FROM workersLogTbl wl WHERE wl.workerId = w.workerId) as LastLogTime,
(SELECT MIN(wl.workerLogTime) FROM workersLogTbl wl WHERE wl.workerId = w.workerId) as FirstLogTime
FROM workersTbl w
WHERE (w.workerId = 5)
side note:
Don't name your tables with Tbl on the end. It's obvious that is a table and doesn't need the suffix and is simply noise. Also, use regular capitalization for the column names. ie: WorkerId instead of workerId