PostgreSQL: sub-queries and aggregate functions(Sum) - sql

I tried referring to other questions; I've inferred that sub-queries cannot be used on aggregate functions, but I cannot solve this use case.
Tables:
1. CustomerInfo(c_id,name)
2. ProductInfo(p_id,price)
3. ModelInfo(p_id,m_id,name)
4. PurchaseRecords(c_id,m_id,quantity)
Required output:
List of customer names, with total amount purchased by each customer.
My flow of thought is that:
Link PurchaseRecords with ModelInfo to get p_id,
ModelInfo with ProductInfo to get the price,
Multiply price returned by quantity in PurchaseRecords for every specific customer,
which requires me to link CustomerInfo in the end to get the name.
I'm using Postgres. I could write a program for that in Java, but I find it hard to do it with SQL. So, what is the correct query here? Any pointers on how to think problems out are appreciated!

SELECT
c.name as customer_name,
sum(coalesce(p.price, 0) * coalesce(pr.quantity, 0)) as amount_purchased
from
CustomerInfo c
left join PurchaseRecords pr on c.c_id = pr.c_id
left join ModelInfo mi on mi.m_id = pr.m_id
left join ProductInfo p on p.p_id = mi.p_id
group by
c.name

Related

Use group by with sum in query

These 3 tables that you see in the image are related
Course table and coaching table and sales table
I want to make a report from this table on how much each coach has sold by each course period.
The query I created is as follows, but unfortunately it has a problem and I do not know where the problem is.
Please help me fix the problem
Thank you
SELECT
dbo.tblCustomersOrders.id, dbo.tblCustomersOrders.pid, dbo.tblPost.postTitle,
dbo.tblArticleAuthor.authorName, SUM(dbo.tblCustomersOrders.prodPrice) AS TotalBuys
FROM
dbo.tblPost
INNER JOIN
dbo.tblArticleAuthor ON dbo.tblPost.id = dbo.tblArticleAuthor.articleID
INNER JOIN
dbo.tblCustomersOrders ON dbo.tblPost.id = dbo.tblCustomersOrders.pid
GROUP BY dbo.tblCustomersOrders.pid
For this use, SUM() is an Aggregate Function, so you need to refer all the
fields that you want to get in your result set.
Example:
SELECT
dbo.tblCustomersOrders.id, dbo.tblCustomersOrders.pid, dbo.tblPost.postTitle,
dbo.tblArticleAuthor.authorName, SUM(dbo.tblCustomersOrders.prodPrice) AS TotalBuys
FROM dbo.tblPost
INNER JOIN
dbo.tblArticleAuthor ON dbo.tblPost.id = dbo.tblArticleAuthor.articleID
INNER JOIN
dbo.tblCustomersOrders ON dbo.tblPost.id = dbo.tblCustomersOrders.pid
GROUP BY dbo.tblCustomersOrders.id, dbo.tblCustomersOrders.pid,
dbo.tblPost.postTitle, dbo.tblArticleAuthor.authorName
But this query does not solve the need for your report.
If you just need to get "how much each coach has sold by each course" , you can try the query bellow.
SELECT
dbo.tblArticleAuthor.authorName, dbo.tblPost.postTitle,
SUM(dbo.tblCustomersOrders.prodPrice) AS TotalBuys
FROM dbo.tblPost
INNER JOIN
dbo.tblArticleAuthor ON dbo.tblPost.id = dbo.tblArticleAuthor.articleID
INNER JOIN
dbo.tblCustomersOrders ON dbo.tblPost.id = dbo.tblCustomersOrders.pid
GROUP BY dbo.tblArticleAuthor.authorName, dbo.tblPost.postTitle
If you need, send more details regarding the desired result.
Here you can find more information about SQL SERVER Aggregate Functions:
https://learn.microsoft.com/en-us/sql/t-sql/functions/aggregate-functions-transact-sql?view=sql-server-ver15
And here a quick example regarding SQL Aliases to build queries with a simple
and effective way:
https://www.w3schools.com/sql/trysql.asp?filename=trysql_select_alias_table
Per your description of the task, the problem is that you only GROUPed BY dbo.tblCustomersOrders.pid, which is the period's id I guess, but you also need to GROUP BY the coach, which is dbo.tblArticleAuthor.authorName, I guess again. Plus in the SELECT field list you can not use more columns only that are aggregated + GROUPed.

Calculate number of distinct instances of value in column

long time lurker. I've searched and searched though none of the solutions work for me.
I'm working in a Sybase (ASE) db (most mssql/mysql transactional db solutions will work just fine)
In my example, I'm trying to calculate/count the number of times a specific 'party_id' is listed in a column. The problem I'm having is that it's only counting FOR each row- so of course the count is always going to be 1.
See output:
(I would like for party_id 130568 to show '2' in the refs column, 125555 to show '5', etc.)
output
Here is my query:
select
count(distinct p.party_id) as refs,
p.party_id,
sp_first_party(casenum),
c.casenum,
mld.mailing_list,
p.our_client
from cases c
inner join party p on c.casenum=p.case_id
inner join names n on n.names_id=p.party_id
inner join mailing_list_defined mld on n.names_id=mld.names_id
where
mld.mailing_list like 'Mattar Stars'
and mld.addr_type like 'Home'
and n.deceased='N'
and p.our_client='Y'
group by p.party_id, c.casenum, mld.mailing_list, p.our_client
order by sp_first_party(casenum) asc
Any tips would be greatly appreciated.
Thank you
Sounds like you need to be using an APPLY statement. Not sure if the join criteria on the APPLY statement is correct, but you should be able to extrapolate the logic. See if that will work with Sybase.
SELECT pic.PartyInstanceCount AS refs
,p.party_id
,sp_first_party(casenum)
,c.casenum
,mld.mailing_list
,p.our_client
FROM cases AS c
INNER JOIN party AS p ON c.casenum = p.case_id
INNER JOIN names AS n ON n.names_id = p.party_id
INNER JOIN mailing_list_defined AS mld ON n.names_id = mld.names_id
OUTER APPLY (
SELECT COUNT(1) AS PartyInstanceCount
FROM party p2
WHERE p2.case_id = c.casenum
) pic
WHERE mld.mailing_list LIKE 'Mattar Stars'
AND mld.addr_type LIKE 'Home'
AND n.deceased = 'N'
AND p.our_client = 'Y'
ORDER BY
sp_first_party(casenum) ASC

"Your query does not include the specified expression..."

I have tried endless things to get this to work and it seems to break over and over again and not work. I'm trying to GROUP BY product after I have calculated the field quantity returned/quantity ordered, but I get the error
your query does not include the specified expression 'quantity_returned/quantity_ordered' as part of an aggregate function.
I do not want to GROUP BY quantity_returned, quantity_ordered, and product, I only want to GROUP BY product.
Here's what my SQL looks like currently...
SELECT
quantity_returned/quantity_ordered AS percentage_returned,
quantity_returned,
quantity_ordered,
returns_fact.product
FROM
Customer_dimension
INNER JOIN
(
Product_dimension
INNER JOIN
(
Day_dimension
INNER JOIN
returns_fact
ON Day_dimension.day_key = returns_fact.day_key
)
ON Product_dimension.product_key = returns_fact.product_key
)
ON Customer_dimension.customer_key = returns_fact.customer_key
GROUP BY returns_fact.product;
When you use a group by you need to actually include everything in your select that isn't a aggregate function.
I have no idea how your tables are set up, but I am throwing a blind dart. If you provide fields in each of the 4 tables someone will be better able to help.
SELECT returns_fact.product, count(quantity_returned), count(quantity_ordered), count(quantity_returned)/count(quantity_ordered) as percentage returned

Include missing years in Group By query

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]
;

Total price from different tables

I have a database with customers, items and orders. This is an exam project, so is maybe not the best for real life. I have this problem. I want a list of what all our customers have bought and a total price of that, but I can't get anything to work.
select Kunder.navn,Ordre.*, Indeholder.antal, Varer.*
from Kunder
join Ordre on Kunder.kunde_nr=Ordre.kunde_nr
join Indeholder on Ordre.ordre_nr=Indeholder.ordre_nr
join Varer on Varer.vare_nr=Indeholder.vare_nr
where er_industri=0
order by bestillingsdato
I have tried a lot like:
sum (Indeholder.antal * Varer.privat_pris) as total
group by Ordre.ordre_nr
But I just can't get anything that I've tried, to give me what I'm looking for.
I hope that you want to help me, and that you understand what I mean (I'm not a native english speaker).
I have uploaded an image of our mapping, so you can see what our database look like:
And for clarity, just a translation:
Kunder = customers
Varer = items
Ordre = orders
Indeholder = includes
Just add more columns on your group by clause.
Apart from the aggregate functions [SUM(), COUNT(), AGV()] the same list of columns must be present at the group by clause
and at select clause:
So, generally:
select <col1, col2, col3...>, SUM(...)
from ...
group by <col1, col2, col3...>
If you want a per customer AND order groupping:
select Kunder.navn, Ordre.ordre_nr, sum (Indeholder.antal * Varer.privat_pris) as total
from Kunder
join Ordre on Kunder.kunde_nr=Ordre.kunde_nr
join Indeholder on Ordre.ordre_nr=Indeholder.ordre_nr
join Varer on Varer.vare_nr=Indeholder.vare_nr
where er_industri=0
group by Kunder.navn, Ordre.ordre_nr
You could also do a per customer groupping:
select Kunder.navn, sum (Indeholder.antal * Varer.privat_pris) as total
from Kunder
join Ordre on Kunder.kunde_nr=Ordre.kunde_nr
join Indeholder on Ordre.ordre_nr=Indeholder.ordre_nr
join Varer on Varer.vare_nr=Indeholder.vare_nr
where er_industri=0
group by Kunder.navn