My Discount model has one Period association. I am trying to write a scope that select discounts that starts today, this includes:
when it has a period, select those periods that begins today.
when it does not have a period, select those discounts which were created between yesterday and today
My current query can do the first requirement (actually a bit complex than this):
def self.begins_today
joins(:event).where("begin = ?", today)
end
However how can I achieve requirement 2?
I was thinking of using SQL UNION command, but I think it can't work as a scope.
I'm assuming event contains the period association?
In any case you want a left join between the discounts table and the periods table. This will give you the period data to do the begin = today where clause, and null if there is no period. Thus the SQL to select the data would be
SELECT [columns]
FROM discounts_table
LEFT JOIN periods_table ON periods_table.discount_id = discounts_table.id
WHERE (periods_table.begin = [today]) OR (periods_table.begin IS NULL AND discounts_table.created_at BETWEEN [yesterday] AND [today])
in rails you should be able to achieve this as follows:
Discount
.joins("LEFT JOIN periods_table ON periods_table.discount_id = discounts_table.id")
.where("(periods_table.begin = ?) OR (periods_table.begin IS NULL AND discounts_table.created_at BETWEEN ? AND ?)", today, today, 1.day.ago.to_date)
Unfortunately you need the use SQL statements rather than letting rails create it for you as:
joins with a symbol only creates an INNER JOIN, not a LEFT JOIN
where with symbols, hashes etc will combine conditions using AND, not OR
Related
Good people of the internet, I need your help!
I'm trying to put together some SQL code to create a report. Basically, I'm needing to look at one table - tbl_Schedules - and fetch the maximum of the field SchedDone, which is a regular date field.
This is fair enough. I manage this using GROUP BY and MAX.
The same table also contains SchedFrom and SchedTo fields, and I need to get this from another record, but run alongside this.
Basically, I need a "LatestDate" field (which shows the max SchedDone), and then a "next scheduled" field (or fields), showing when it is next to be done, pulled from a row where the SchedDone is null.
My current code, displayed below (ignore everything but the tbl_Schedules stuff) is working to an extent. It shows the LatestDate as described above, but also shows the maximum of that Task's SchedFrom and SchedTo. These are all from different rows in the tbl_Schedules, which is what I want. I just need to know how to set up rules for the SchedFrom and SchedTo, preferably without involving any other tables or setting up multiple views.
I do have this working, but it's taking up several views and the speed involved is not good. I'd hope I can get it working in a single chunk of SQL code.
PS - tbl_PhysicalAssets is a one-to-many relationship with tbl_Operations (one row in tbl_PhysicalAssets to many in tbl_Operations), and tbl_Operations is a one-to-many relationship with tbl_Schedules (one row in tbl_Operations to many in tbl_Schedules).
Current code below (again, please ignore the other tables!) -
SELECT
dbo.tbl_PhysicalAsset.FKID_Contract,
dbo.tbl_PhysicalAsset.MyLevel,
dbo.tbl_PhysicalAsset.L1_Name,
dbo.tbl_PhysicalAsset.L2_Name,
dbo.tbl_PhysicalAsset.L3_Name,
dbo.tbl_OpList.Operation_Name,
dbo.tbl_Teams.Team_Name,
MAX(tbl_Schedules_1.SchedDone) AS LatestDate,
MAX(tbl_Schedules_1.SchedFrom) AS Expr1,
MAX(tbl_Schedules_1.SchedTo) AS Expr2
FROM
dbo.tbl_Schedules AS tbl_Schedules_1
RIGHT OUTER JOIN
dbo.tbl_PhysicalAsset
INNER JOIN
dbo.tbl_Operations ON dbo.tbl_PhysicalAsset.PKID_PhysicalAsset = dbo.tbl_Operations.FKID_PhysicalAsset
INNER JOIN
dbo.tbl_OpList ON dbo.tbl_Operations.FKID_Operation = dbo.tbl_OpList.PKID_Op
INNER JOIN
dbo.tbl_Teams ON dbo.tbl_Operations.FKID_Team = dbo.tbl_Teams.PKID_Team ON tbl_Schedules_1.FKID_Operation = dbo.tbl_Operations.PKID_Operation
GROUP BY
dbo.tbl_PhysicalAsset.FKID_Contract,
dbo.tbl_PhysicalAsset.MyLevel,
dbo.tbl_PhysicalAsset.L1_Name,
dbo.tbl_PhysicalAsset.L2_Name,
dbo.tbl_PhysicalAsset.L3_Name,
dbo.tbl_OpList.Operation_Name,
dbo.tbl_Teams.Team_Name
HAVING
(dbo.tbl_PhysicalAsset.FKID_Contract = 6)
AND (dbo.tbl_PhysicalAsset.MyLevel = 3)
This is rough as we don't know the exact details of your table structure.
But basically you need to first write the queries that get the two separate bits of information, make sure they work in isolation. You can then just join them together.
So something like (I've assumed FKID_Operation is the 'common' piece of info):
select
a.FKID_Operation
, b.LatestDate
, c.NextToDate
, c.NextFromDate
from tbl_Schedules a
inner join
(
select
m.FKID_Operation
, Max(m.SchedDone) as LatestDate
from tbl_Schedules m
where SchedDone is not null
) b
on a.FKID_Operation = b.FKID_Operation
inner join
(
select
n.FKID_Operation
, n.SchedTo as NextToDate
, n.SchedFrom as NextFromDate
from tbl_Schedules n
where SchedDone is null
) c
on a.FKID_Operation = c.FKID_Operation
I'd also look into CTE's as they can make this kind of query much easier to understand.
I am fairly new in Access and SQL programming. I am trying to do the following:
Sum(SO_SalesOrderPaymentHistoryLineT.Amount) AS [Sum Of PaymentPerYear]
and group by year even when there is no amount in some of the years. I would like to have these years listed as well for a report with charts. I'm not certain if this is possible, but every bit of help is appreciated.
My code so far is as follows:
SELECT
Base_CustomerT.SalesRep,
SO_SalesOrderT.CustomerId,
Base_CustomerT.Customer,
SO_SalesOrderPaymentHistoryLineT.DatePaid,
Sum(SO_SalesOrderPaymentHistoryLineT.Amount) AS [Sum Of PaymentPerYear]
FROM
Base_CustomerT
INNER JOIN (
SO_SalesOrderPaymentHistoryLineT
INNER JOIN SO_SalesOrderT
ON SO_SalesOrderPaymentHistoryLineT.SalesOrderId = SO_SalesOrderT.SalesOrderId
) ON Base_CustomerT.CustomerId = SO_SalesOrderT.CustomerId
GROUP BY
Base_CustomerT.SalesRep,
SO_SalesOrderT.CustomerId,
Base_CustomerT.Customer,
SO_SalesOrderPaymentHistoryLineT.DatePaid,
SO_SalesOrderPaymentHistoryLineT.PaymentType,
Base_CustomerT.IsActive
HAVING
(((SO_SalesOrderPaymentHistoryLineT.PaymentType)=1)
AND ((Base_CustomerT.IsActive)=Yes))
ORDER BY
Base_CustomerT.SalesRep,
Base_CustomerT.Customer;
You need another table with all years listed -- you can create this on the fly or have one in the db... join from that. So if you had a table called alltheyears with a column called y that just listed the years then you could use code like this:
WITH minmax as
(
select min(year(SO_SalesOrderPaymentHistoryLineT.DatePaid) as minyear,
max(year(SO_SalesOrderPaymentHistoryLineT.DatePaid) as maxyear)
from SalesOrderPaymentHistoryLineT
), yearsused as
(
select y
from alltheyears, minmax
where alltheyears.y >= minyear and alltheyears.y <= maxyear
)
select *
from yearsused
join ( -- your query above goes here! -- ) T
ON year(T.SO_SalesOrderPaymentHistoryLineT.DatePaid) = yearsused.y
You need a data source that will provide the year numbers. You cannot manufacture them out of thin air. Supposing you had a table Interesting_year with a single column year, populated, say, with every distinct integer between 2000 and 2050, you could do something like this:
SELECT
base.SalesRep,
base.CustomerId,
base.Customer,
base.year,
Sum(NZ(data.Amount)) AS [Sum Of PaymentPerYear]
FROM
(SELECT * FROM Base_CustomerT INNER JOIN Year) AS base
LEFT JOIN
(SELECT * FROM
SO_SalesOrderT
INNER JOIN SO_SalesOrderPaymentHistoryLineT
ON (SO_SalesOrderPaymentHistoryLineT.SalesOrderId = SO_SalesOrderT.SalesOrderId)
) AS data
ON ((base.CustomerId = data.CustomerId)
AND (base.year = Year(data.DatePaid))),
WHERE
(data.PaymentType = 1)
AND (base.IsActive = Yes)
AND (base.year BETWEEN
(SELECT Min(year(DatePaid) FROM SO_SalesOrderPaymentHistoryLineT)
AND (SELECT Max(year(DatePaid) FROM SO_SalesOrderPaymentHistoryLineT))
GROUP BY
base.SalesRep,
base.CustomerId,
base.Customer,
base.year,
ORDER BY
base.SalesRep,
base.Customer;
Note the following:
The revised query first forms the Cartesian product of BaseCustomerT with Interesting_year in order to have base customer data associated with each year (this is sometimes called a CROSS JOIN, but it's the same thing as an INNER JOIN with no join predicate, which is what Access requires)
In order to have result rows for years with no payments, you must perform an outer join (in this case a LEFT JOIN). Where a (base customer, year) combination has no associated orders, the rest of the columns of the join result will be NULL.
I'm selecting the CustomerId from Base_CustomerT because you would sometimes get a NULL if you selected from SO_SalesOrderT as in the starting query
I'm using the Access Nz() function to convert NULL payment amounts to 0 (from rows corresponding to years with no payments)
I converted your HAVING clause to a WHERE clause. That's semantically equivalent in this particular case, and it will be more efficient because the WHERE filter is applied before groups are formed, and because it allows some columns to be omitted from the GROUP BY clause.
Following Hogan's example, I filter out data for years outside the overall range covered by your data. Alternatively, you could achieve the same effect without that filter condition and its subqueries by ensuring that table Intersting_year contains only the year numbers for which you want results.
Update: modified the query to a different, but logically equivalent "something like this" that I hope Access will like better. Aside from adding a bunch of parentheses, the main difference is making both the left and the right operand of the LEFT JOIN into a subquery. That's consistent with the consensus recommendation for resolving Access "ambiguous outer join" errors.
Thank you John for your help. I found a solution which works for me. It looks quiet different but I learned a lot out of it. If you are interested here is how it looks now.
SELECT DISTINCTROW
Base_Customer_RevenueYearQ.SalesRep,
Base_Customer_RevenueYearQ.CustomerId,
Base_Customer_RevenueYearQ.Customer,
Base_Customer_RevenueYearQ.RevenueYear,
CustomerPaymentPerYearQ.[Sum Of PaymentPerYear]
FROM
Base_Customer_RevenueYearQ
LEFT JOIN CustomerPaymentPerYearQ
ON (Base_Customer_RevenueYearQ.RevenueYear = CustomerPaymentPerYearQ.[RevenueYear])
AND (Base_Customer_RevenueYearQ.CustomerId = CustomerPaymentPerYearQ.CustomerId)
GROUP BY
Base_Customer_RevenueYearQ.SalesRep,
Base_Customer_RevenueYearQ.CustomerId,
Base_Customer_RevenueYearQ.Customer,
Base_Customer_RevenueYearQ.RevenueYear,
CustomerPaymentPerYearQ.[Sum Of PaymentPerYear]
;
My query below is doubling the amount on the last record it returns. I have 3 tables - activities, bookings and tempbookings. The query needs to list the activities and attached information and pull the total number (using the SUM) of places booked (as BookingTotal) from the booking table by each activity and then it needs to calculate the same for tempbookings (as tempPlacesReserved) providing the reservedate field inside that table is in the future.
However the first issue is that if there are no records for an activity in the tempbookings table it does not return any records for that activity at all, to get around this i created dummy records in the past so that it still returns the record, but if I can make it so I don't have to do this I would prefer it!
The main issue I have is that on the final record of the returned results it doubles the booking total and the places reserved which of course makes the whole query useless.
I know that I am doing something wrong I just haven't been able to sort it, I have searched similar issues online but am unable to apply them to my situation correctly.
Any help would be appreciated.
P.S. I'm aware that normally you wouldn't need to fully label all the paths to the databases, tables and fields as I have but for the program I am planning to use it in I have to do it this way.
Code:
SELECT [LeisureActivities].[dbo].[activities].[activityID],
[LeisureActivities].[dbo].[activities].[activityName],
[LeisureActivities].[dbo].[activities].[activityDate],
[LeisureActivities].[dbo].[activities].[activityPlaces],
[LeisureActivities].[dbo].[activities].[activityPrice],
SUM([LeisureActivities].[dbo].[bookings].[bookingPlaces]) AS 'bookingTotal',
SUM (CASE WHEN[LeisureActivities].[dbo].[tempbookings].[tempReserveDate] > GetDate() THEN [LeisureActivities].[dbo].[tempbookings].[tempPlaces] ELSE 0 end) AS 'tempPlacesReserved'
FROM [LeisureActivities].[dbo].[activities],
[LeisureActivities].[dbo].[bookings],
[LeisureActivities].[dbo].[tempbookings]
WHERE ([LeisureActivities].[dbo].[activities].[activityID]=[LeisureActivities].[dbo].[bookings].[activityID]
AND [LeisureActivities].[dbo].[activities].[activityID]=[LeisureActivities].[dbo].[tempbookings].[tempActivityID])
AND [LeisureActivities].[dbo].[activities].[activityDate] > GetDate ()
GROUP BY [LeisureActivities].[dbo].[activities].[activityID],
[LeisureActivities].[dbo].[activities].[activityName],
[LeisureActivities].[dbo].[activities].[activityDate],
[LeisureActivities].[dbo].[activities].[activityPlaces],
[LeisureActivities].[dbo].[activities].[activityPrice];
Your current query is using an INNER JOIN between each of the tables so if the tempBookings table has no records, you will not return anything.
I would advise that you start to use JOIN syntax. You might also need to use subqueries to get the totals.
SELECT a.[activityID],
a.[activityName],
a.[activityDate],
a.[activityPlaces],
a.[activityPrice],
coalesce(b.bookingTotal, 0) bookingTotal,
coalesce(t.tempPlacesReserved, 0) tempPlacesReserved
FROM [LeisureActivities].[dbo].[activities] a
LEFT JOIN
(
select activityID,
SUM([bookingPlaces]) AS bookingTotal
from [LeisureActivities].[dbo].[bookings]
group by activityID
) b
ON a.[activityID]=b.[activityID]
LEFT JOIN
(
select tempActivityID,
SUM(CASE WHEN [tempReserveDate] > GetDate() THEN [tempPlaces] ELSE 0 end) AS tempPlacesReserved
from [LeisureActivities].[dbo].[tempbookings]
group by tempActivityID
) t
ON a.[activityID]=t.[tempActivityID]
WHERE a.[activityDate] > GetDate();
Note: I am using aliases because it is easier to read
Use new SQL-92 Join syntax, and make join to tempBookings an outer join. Also clean up your sql with table aliases. Makes it easier to read. As to why last row has doubled values, I don't know, but on off chance that it is caused by extra dummy records you entered. get rid of them. That problem is fixed by using outer join to tempBookings. The other possibility is that the join conditions you had to the tempBookings table(t.tempActivityID = a.activityID) is insufficient to guarantee that it will match to only one record in activities table... If, for example, it matches to two records in activities, then the rows from Tempbookings would be repeated twice in the output, (causing the sum to be doubled)
SELECT a.activityID, a.activityName, a.activityDate,
a.activityPlaces, a.activityPrice,
SUM(b.bookingPlaces) bookingTotal,
SUM (CASE WHEN t.tempReserveDate > GetDate()
THEN t.tempPlaces ELSE 0 end) tempPlacesReserved
FROM LeisureActivities.dbo.activities a
Join LeisureActivities.dbo.bookings b
On b.activityID = a.activityID
Left Join LeisureActivities.dbo.tempbookings t
On t.tempActivityID = a.activityID
WHERE a.activityDate > GetDate ()
GROUP BY a.activityID, a.activityName,
a.activityDate, a.activityPlaces,
a.activityPrice;
I have a PHP page running in postgres. I have 3 tables - workorders, wo_parts and part2vendor. I am trying to multiply 2 table column row datas together, ie wo_parts has a field called qty and part2vendor has a field called cost. These 2 are joined by wo_parts.pn and part2vendor.pn. I have created a query like this:
$scoreCostQuery = "SELECT SUM(part2vendor.cost*wo_parts.qty) as total_score
FROM part2vendor
INNER JOIN wo_parts
ON (wo_parts.pn=part2vendor.pn)
WHERE workorder=$workorder";
But if I add the costs of the parts multiplied by the qauntities supplied, it adds to a different number than what the script is doing. Help....I am new to this but if someone can show me in SQL I can modify it for postgres. Thanks
Without seeing example data, there's no way for us to know why you're query totals are coming out differently that when you do the math by hand. It could be a bad join, so you are getting more/less records than you expected. It's also possible that your calculations are off. Pick an example with the smallest number of associated records & compare.
My suggestion is to add a GROUP BY to the query:
SELECT SUM(p.cost * wp.qty) as total_score
FROM part2vendor p
JOIN wo_parts wp ON wp.pn = p.pn
WHERE workorder = $workorder
GROUP BY workorder
FYI: MySQL was designed to allow flexibility in the GROUP BY, while no other db I've used does - it's a source of numerous questions on SO "why does this work in MySQL when it doesn't work on db x...".
To Check that your Quantities are correct:
SELECT wp.qty,
p.cost
FROM WO_PARTS wp
JOIN PART2VENDOR p ON p.pn = wp.pn
WHERE p.workorder = $workorder
Check that the numbers are correct for a given order.
You could try a sub-query instead.
(Note, I don't have a Postgres installation to test this on so consider this more like pseudo code than a working example... It does work in MySQL tho)
SELECT
SUM(p.`score`) AS 'total_score'
FROM part2vendor AS p2v
INNER JOIN (
SELECT pn, cost * qty AS `score`
FROM wo_parts
) AS p
ON p.pn = p2v.pn
WHERE p2n.workorder=$workorder"
In the question, you say the cost column is in part2vendor, but in the query you reference wo_parts.cost. If the wo_parts table has its own cost column, that's the source of the problem.
We have a database that stores vehicle's gps position, date, time, vehicle identification, lat, long, speed, etc., every minute.
The following select pulls each vehicle position and info, but the problem is that returns the first record, and I need the last record (current position), based on date (datagps.Fecha) and time (datagps.Hora). This is the select:
SELECT configgps.Fichagps,
datacar.Ficha,
groups.Nombre,
datagps.Hora,
datagps.Fecha,
datagps.Velocidad,
datagps.Status,
datagps.Calleune,
datagps.Calletowo,
datagps.Temp,
datagps.Longitud,
datagps.Latitud,
datagps.Evento,
datagps.Direccion,
datagps.Provincia
FROM asigvehiculos
INNER JOIN datacar ON (asigvehiculos.Iddatacar = datacar.Id)
INNER JOIN configgps ON (datacar.Configgps = configgps.Id)
INNER JOIN clientdata ON (asigvehiculos.Idgroup = clientdata.group)
INNER JOIN groups ON (clientdata.group = groups.Id)
INNER JOIN datagps ON (configgps.Fichagps = datagps.Fichagps)
Group by Fichagps;
I need same result I'm getting, but instead of the older record I need the most recent
(LAST datagps.Fecha / datagps.Hora).
How can I accomplish this?
Add ORDER BY datagps.Fecha DESC, datagps.Hora DESC LIMIT 1 to your query.
I'm not sure why you are having any problems with this as Lex's answers seem good.
I would start putting ORDER BY's in your query so it puts them in an order, when it's showing the record you want as the first one in the list, then add the LIMIT.
If you want the most recent, then the following should be good enough:
ORDER BY datagps.Fecha DESC, datagps.Hora DESC
If you simply want the record that was added to the database most recently (irregardless of the date/time fields), then you could (assuming you have an auto-incremental primary key in the datagps table (I assume it's called dataID for this example)):
ORDER BY datagps.dataID DESC
If these aren't showing the data you want - then there is something missing from your example (maybe data-types aren't DATETIME fields? - if not - then maybe a CONVERT to change them from their current type before ORDERing BY would be a good idea)
EDIT:
I've seen the screenshot and I'm confused as to what the issue is still. That appears to be showing everything in order. Are you implying that there are many more than 5 records? How many are you expecting?
Do you mean: for each record returned, you want the one row from the table datagps with the latest date and time attached to the result? If so, how about this:
# To show how the query will be executed
# comment to return actual results
EXPLAIN
SELECT
configgps.Fichagps, datacar.Ficha, groups.Nombre, datagps.Hora, datagps.Fecha,
datagps.Velocidad, datagps.Status, datagps.Calleune, datagps.Calletowo,
datagps.Temp, datagps.Longitud, datagps.Latitud, datagps.Evento,
datagps.Direccion, datagps.Provincia
FROM asigvehiculos
INNER JOIN datacar ON (asigvehiculos.Iddatacar = datacar.Id)
INNER JOIN configgps ON (datacar.Configgps = configgps.Id)
INNER JOIN clientdata ON (asigvehiculos.Idgroup = clientdata.group)
INNER JOIN groups ON (clientdata.group = groups.Id)
INNER JOIN datagps ON (configgps.Fichagps = datagps.Fichagps)
########### Add this section
LEFT JOIN datagps b ON (
configgps.Fichagps = b.Fichagps
# wrong condition
#AND datagps.Hora < b.Hora
#AND datagps.Fecha < b.Fecha)
# might prevent indexes to be used
AND (datagps.Fecha < b.Fecha OR (datagps.Fecha = b.Fecha AND datagps.Hora < b.Hora))
WHERE b.Fichagps IS NULL
###########
Group by configgps.Fichagps;
Similar question here only that that one uses outer joins.
Edit (again):
The conditions are wrong so corrected it. Can you show us the output of the above EXPLAIN query so we can pinpoint where the bottle neck is?
As hurikhan77 said, it will be better if you could convert both of the the columns into a single datetime field - though I'm guessing this would not be possible for your case (since your database is already being used?)
Though if you can convert it, the condition (on the join) would become:
AND datagps.FechaHora < b.FechaHora
After that, add an index for datagps.FechaHora and the query would be fast(er).
What you probably want is getting the maximum of (Fecha,Hora) per grouped dataset? This is a little complicated to accomplish with your column types. You should combine Fecha and Hora into one column of type DATETIME. Then it's easy to just SELECT MAX(FechaHora) ... GROUP BY Fichagps.
It could have helped if you posted your table structure to understand the problem.