I don't know a lot about MyQSL.
Here is my code (to extract code from a monitoring tool)
SELECT DISTINCT
FROM_UNIXTIME(data_bin.ctime), index_data.host_name, index_data.service_description, metrics.metric_name, data_bin.value
FROM metrics
inner join index_data ON index_data.id = metrics.index_id
inner join data_bin ON data_bin.id_metric = metrics.metric_id
ORDER BY data_bin.ctime;
Despites my efforts, I don't manage to :
Filter by timerange (with human readable time)
Obtain that output :
Timerange, Hostname, ServiceA, metricA1, metricA2, ... ServiceB, metricB1, metricB2 ...
-> the goal is to group by identical Timerange and Hostname
I think your question is missing some key points, and I'll adjust this if you can specify what you're looking for a bit better with some example data from each of these tables.
But in the meantime, I think I have a good understanding, maybe this is what you're looking for:
SELECT DISTINCT
FROM_UNIXTIME(data_bin.ctime) AS timerange, index_data.host_name, index_data.service_description, metrics.metric_name, data_bin.value
FROM metrics
inner join index_data ON index_data.id = metrics.index_id
inner join data_bin ON data_bin.id_metric = metrics.metric_id
GROUP BY index_data.host_name, timerange
ORDER BY timerange;
Related
I have a SQL query that links 2 tables to provide the data if a horse is in both the tables:
SELECT ProformSystem.TheDate as racedate,
ProformSystem.Course as course,
ProformSystem.TheTime as thetime,
ProformSystem.Horse as horse,
ATRSpeedRatings.rank as rank
FROM ATRSpeedRatings
INNER JOIN ProformSystem ON (ATRSpeedRatings.Horse = trim(ProformSystem.Horse)) AND (ATRSpeedRatings.TheDate = ProformSystem.TheDate) order by ProformSystem.TheTime;"
Is it possible that if the horse in ProformSystem.Horse is NOT in ATRSpeedRatings.Horse then I just make rank = 0 as a default value, or would I need to run a separate query?
This way I can display all horses from ProformSystem even if they don't have a rank in ATRSpeedRatings.
I think you want a left join and coalesce():
SELECT ps.TheDate as racedate, ps.Course as course, ps.TheTime as thetime,
ps.Horse as horse, COALESCE(sr.rank, 0) as rank
FROM ProformSystem ps LEFT JOIN
ATRSpeedRatings sr
ON sr.Horse = TRIM(ps.Horse) AND sr.TheDate = ps.TheDate)
ORDER BY ps.TheTime;
Note that this query uses table aliases. These make the query easier to write and to read.
Also, the JOIN condition sr.Horse = trim(ps.Horse) is highly suspect. You should fix the data so there are no spaces in ProformSystem. Fixing the data is more efficient and it will prevent problems on future queries.
I have a rather big SQL statement that I am working with in MS Access 2010. Here it goes:
SELECT
W.ID AS wid,
W.wpt_ty AS ty,
W.wpt_num AS num,
W.wpt_nxt AS nxt,
W.latdeg AS lat,
W.londeg AS lon,
W.alt AS alt,
W.mission_id AS mid,
W.ctg1 AS ctg1,
W.ctg2 AS ctg2,
W.ctg3 AS ctg3,
W.ctg4 AS ctg4,
W.wpt_index AS indx,
W.vel AS vel,
W.tu AS tu,
R.route_num AS rnum,
R.AC_num AS ac,
R.route_type AS rtype,
R.LastUpdatedOn AS d8,
R.LastUpdatedBy AS auth,
R.flight_wpt_count AS wfcount,
M.mission_name AS msnName,
V.Description AS vstatus,
R.disallowed_reason_id AS did,
CW.wpt_num AS c1num,
CR.matching_route_id AS c1mrid,
CW.wpt_index AS c1indx,
CRU.runway_name AS c1rnwy,
CR.route_num AS c1rnum
FROM Validation AS V
(RIGHT JOIN Runways AS CRU
INNER JOIN (Routes CR
INNER JOIN Waypoints CW ON CR.ID = CW.route_id)
ON Runways.ID = Routes.runway_id
INNER JOIN ((Missions as M
INNER JOIN Routes AS R ON M.ID = R.mission_id)
INNER JOIN Waypoints AS W ON (R.ID = W.route_id)
AND (M.ID = W.mission_id)) ON
V.ID = R.validated
WHERE (((R.matching_route_id)=307543) AND ((R.validated) <> 0 ))
AND (((CW.mission_id)=mid) AND ((CW.wpt_num) = (ctg1))))
If you look at the bottom, you can see am I referencing the values ctg1 and mid on a Right Join while the Inner Joins reference other literal values. Eventually I will want to do the same for ctg2, ctg3, and ctg4
Right now I am running these as 2 separate queries but finding it to be way too slow. If I can join combine the queries (sort of like how I am showing here) it could speed things up greatly. But I am at a loss for how to:
Using select values earlier in said query from the Inner/Left join and push them into values needed on the Right join.
I may be using joins incorrectly, but I thought they had to do with combining data from possible the same tables, just on different pivot points.
How to use the MS Access GUI to help write a query like this.
I know this is for MS Access but I am tagging for MySQL just in case there are similar queries there which can be ported to MS Access?
Have you tried using UNION for this?
It would allow you to execute this query (As two queries, which you mentioned as a possibility), and join the results for your output.
Be warned, it will eat up (only show one of) your duplicates in the results set.
I also suggest reading up on the different types of joins for your own benefit, in the following answer:
MYSQL Joins
I'm sure someone will have a very simple answer to this but I can't work it out for the life of me: I have 3 tables that look something like this:
Vehicles: Vehicle_id, Reg_number...
Datalogger: Logger_id, event, status, date...
Vehicle_Loggers: Vehicle_id, Logger_id, installed_from, installed_to
(Relationships are on columns with the same name here)
Using these tables how would I get the whole history of a given vehicle's logs (event and status) even if it has had multiple loggers fitted at different times?
I know this can be done using a cursor but as this is really a set operation (Get the set of loggers that have been attached to the vehicle, then get the reports of each logger using the given date range for that logger)
EDIT: Loggers can be used in more than one vehicle during their lifetime, hence the inclusion of the dates.
Thanks
Gareth
You can do it like this:
select v.Reg_number, d.* from Vehicles v
inner join Vehicle_Loggers vl on vl.Vehicle_id = v.Vehicle_id
inner join Datalogger d on d.Logger_id = vl.Logger_Id
where v.Reg_number = ...
Just replace the Reg_number for the intended one.
To take in account the dates, possibly would be like this:
select v.Reg_number, d.* from Vehicles v
inner join Vehicle_Loggers vl on vl.Vehicle_id = v.Vehicle_id
inner join Datalogger d on d.Logger_id = vl.Logger_Id and d.date between vl.installed_from and vl.installed_to
where v.Reg_number = ...
I'm trying to reference a field from the 1st select table in the 3rd select(subquery) table.
However, that field isn't recognized when it goes to that sub-level of a query.
The php code I'm working on uses sql to return part of the sql command (string) that will be used in other places.
I've came up with this example that shows up the kind of nested querys that I want to solve.
In here I'm trying to get the name and emails of users that are working at night and have a matching job rank for an available job:
tables -----------> fields
table_users -> [user_id, name, email, rank, ...]
table_users_jobs -> [user_id, job_id, period, ....]
table_jobs -> [job_id, status, rank, ...]
-- sql calling code -> $rank = "t1.rank"; get_users_info_by_rank($rank);
-- maybe using: SET #rank = NULL; SELECT #rank := $rank, t1.name, ...
SELECT t1.name, t1.email
FROM table_users as t1
WHERE t1.user_id IN (
SELECT t2.user_id
FROM table_users_jobs as t2
WHERE t2.period = 'night' AND
t2.job_id IN (
-- avaiable jobs to that rank -> get_job_ranks_sql($rank);
SELECT t3.job_id
FROM table_jobs as t3
-- maybe using: t3.rank = #rank
WHERE t3.rank = t1.rank AND
t3.status = 'avaiable_position')
)
Working a little I guess I could avoid the 3rd level select problem. Nevertheless the point is that I'm trying to reuse sql code like the function that gives me the job_id of the rank that I chose:
function get_job_ranks_sql($rank){
//probably 't3' will be renamed for something more unique
return 'SELECT t3.job_id
FROM table_jobs as t3
WHERE t3.rank = '.$rank.' AND
t3.status = "available_position")';
}
Even using php I'm trying to make it generic to maybe use with another language if possible.
The sql version using is MySQL 5.1.41
Actually I think it's possible the way I want, by using sql variables like #rank, but I'm not sure if it's slower and if there are other better ways to do it.
Thanks in advance for any help :)
So, as one commenter pointed out, I think you would do much better off using JOINS, than sub-selects. For example, if I am reading your query/problem correctly, you could do a join query like this:
SELECT t1.name, t1.email, t3.job_id
FROM table_users t1
LEFT JOIN table_users_job t2
ON t1.user_id = t2.user_id
LEFT JOIN table_jobs t3
ON t3.job_id = t2.job_id
WHERE t2.period = 'night
AND t3.status = 'available_position'
Which is a lot more concise, easier to read, and is easier on your database. But doing this would prevent you from modularizing your SQL. If that is really important, you might consider storing such queries in Stored Procedure. This way, you can actually get a SP to return a list of results. Take a look at this tutorial:
http://www.wellho.net/resources/ex.php4?item=s163/stp4
Of course, that doesn't really solve your problem of being able to access variables at the lower levels of a sub select, but it would make your SQL easier to manage, and make it available to other language implementations, as you mentioned might be a need for you.
Something else to consider, in the bigger picture, would be migrating to a PHP framework that provides an ORM layer, where you could make those tables into objects, and then be able to access your data with much greater ease and flexibility (usually). But that is very 'big picture' and might not be suitable for your project requirements. One such framework that I could recommend, however, is CakePHP.
I wonder if someone can help me. I want to replicate the following SQL query using LINQ in VB.Net.I'm a little unclear on how to do subqueries / aggregates.
Thanks
SELECT *
FROM Server S
INNER JOIN ServerHDD H
ON S.Server_ID = H.Server_ID
INNER JOIN (SELECT MAX(ServerHDD_ID) AS ServerHDD_ID
FROM ServerHDD
GROUP BY Server_ID, Letter) Filter
ON H.ServerHDD_ID = Filter.ServerHDD_ID
ORDER BY S.Hostname, H.Letter
Got this as below in C# => need VB.Net Conversion please.
from S in SERVER
join H in SERVERHDD on S.Server_ID equals H.Server_ID
join FILTER in
(from s in SERVERHDD group s
by new {s.Server_ID, s.Letter}
into groupedServerHDD select new
{
SERVERHDD_ID = groupedServer.Sum(gS=>gS.ServerHDD_ID)
}
)
on H.ServerHDD_ID equals FILTER.SERVERHDD_ID
orderby S.Hostname, H.Letter
select S
This is my most favorite page regarding this topic. I love LINQ to SQL (and wish they intended to continue support for it over Entity Framework...) http://msdn.microsoft.com/en-us/vbasic/bb688085.aspx. On this page you will find all the answers to your querying needs. It is hard to format the query here without something to test it against!
Your inner joins go away with the simple join syntax of LtS. You can either say .Max() on your inner select or Max(pseudo functoid here) like this:
From p2 In g _
Where p2.UnitPrice = g.Max(Function(p3) p3.UnitPrice) _
Select p2
There are a couple of LINQ learning tools out there that are pretty cool.
This one is my favourite... LinqPad. But you might also want to check out Linqer.
You should be able to paste your code into one of them apps and it will show you how its converted. Hope they come in handy :)