I am struggling with this problem in MySQL. The question asks...
Find the names of the individuals and businesses that have made no more than three payments.
Individuals is a table, businesses is a table, and payments is a table. The problem I am having is Payments only contains columns dateFiled and amountPaid. I tried creating a count operation, but it shows blank results.
Here is my code:
SELECT Individuals.name, Businesses.name, Payments.taxpayerID, COUNT(*) AS 'Payments'
FROM Payments
JOIN Individuals ON Payments.taxpayerID=Individuals.taxpayerID
JOIN Businesses ON Payments.taxpayerID=Businesses.taxpayerID
GROUP BY Businesses.name, Individuals.name, Payments.taxpayerID
HAVING COUNT(*) <= 3;
If anyone can help me solve this it would be greatly appreciated.
I guess what you are looking for is not a join of three tables but a union of two selects:
SELECT Individuals.name, Payments.taxpayerID, COUNT(*) AS 'Payments'
FROM Payments
JOIN Individuals ON Payments.taxpayerID=Individuals.taxpayerID
GROUP BY Individuals.name, Payments.taxpayerID
HAVING COUNT(*) <= 3
UNION
SELECT Businesses.name, Payments.taxpayerID, COUNT(*) AS 'Payments'
FROM Payments
JOIN Businesses ON Payments.taxpayerID=Businesses.taxpayerID
GROUP BY Businesses.name, Payments.taxpayerID
HAVING COUNT(*) <= 3;
Your version is giving zero results, because a tax ID is either associated with a business or an individual. Therefore you need to query both independently and combine the results with union.
That said, yes you could work with joins and only a single select but then you'd need outer joins and the query would be less readable IMHO.
Related
I'm trying to join 2 tables and count the number of entries for unique variables in one of the columns. In this case I'm trying to join 2 tables - patients and trials (patients has a FK to trials) and count the number of patients that show up in each trial. This is the code i have so far:
SELECT patients.trial_id, trials.title
FROM trials
JOIN(SELECT patients, COUNT(id) AS Num_Enrolled
FROM patients
GROUP BY trials) AS Trial_Name;
The Outcome I'm trying to acheive is:
Trial_Name Num_Patients
Bushtucker 5
Tribulations 7
I'm completely new to sql and have been struggling with the syntax compared to scripting languages.
It's not 100% clear from your question of the names of your columns however you are after a basic aggregation. Adjust the names of the columns if necessary:
select t.title Trial_Name, Count(*) Num_Patients
from Trials t
join Patients p on p.Trial_Id = t.Id
group by t.title;
Based on Stu-'s answer, I want to say that your column naming is wrong.But you can write query based on logic like this.
SELECT trial.title AS Trial_Name, COUNT(p.id) AS Num_Patients
FROM trial
INNER JOIN patients AS p
ON trial.patient_fk_id = p.id
GROUP BY trial.title,p.id;
Posed a question: What school was attended most frequently?
I came up with the following statement...
select unitid, count(unitid) as 'Times_Occurred'
from people
group by unitid
order by count(*) desc
limit 50;
I made it limit 50 because multiple unitid's had 3. I have two tables, a people table, and a post table. They are connected by unitid. I am trying to figure out how to do an inner join to get not only the top 50 highest unitid's, and how often they occur, but also the colleges that go along with those Id's.
Any and all help is much appreciated!!
Perhaps your counts are being inflated and you don't know how to handle that... this is one approach using an inline view. The reason this works is because the counts are calculated and retained prior to the join. Thus the 1-M cardinality doesn't negatively effect the counts.
Select *
from (
select unitid, count(unitid) as 'Times_Occurred'
from people
group by unitid
order by count(*) desc
limit 50) A
INNER JOIN Post B
on A.UnitID = B.UnitID
Have the need to run a bit more complex of a MySQL query. I have two tables that I need to join where one contains the primary key on the other. That's easy enough, but then I need to find the number of occurrences of each ID returned as well, and ultimately sort all the results by this number.
Normally this would just be a group by, but I also need to see ALL of the results (so if it were a group by containing 10 records, I'd need to see all 10, as well as that count returned as well).
So for instance, two tables could be:
Customers table:
CustomerID name address phone etc..
Orders table:
OrderID CustomerID product info etc..
The idea is to output, and sort the orders table to find the customer with the most orders in a given time period. The resultant report would have a few hundred customers, along with their order info below.
I couldn't figure out a way to have it return the rows containing ALL the info from both tables, plus the number of occurences of each in one row. (customer info, individual orders info, and count).
I considered separating it into multiple queries (get the list of top customers), then a bunch of sub-queries for each order programmatically. But that was going to end up with many hundreds of sub-queries every time this is submitted.
So I was hoping someone might know of an easier way to do this. My thought was to have a return result with repeated information, but get it only in one query.
Thanks in advance!
SELECT CUST.CustomerID, CUST.Name, ORDR.OrderID, ORDR.OrderDate, ORDR.ProductInfo, COUNTS.cnt
FROM Customers CUST
INNER JOIN Orders ORDR
ON ORDR.CustomerID = CUST.CustomerID
INNER JOIN
(
SELECT C.CustomerID, COUNT(DISTINCT O.OrderID) AS cnt
FROM Customers C
INNER JOIN Orders O
ON O.CustomerID = C.CustomerID
GROUP BY C.CustomerID
) COUNTS
ON COUNTS.CustomerID = CUST.CustomerID
ORDER BY COUNTS.cnt DESC, CustomerID
This will return one row per order, displayed by customer, ordered by the number of orders for that customer.
I have a database where a company has an amount of slots, These slots can be filled with persons..
I want to do a query where I can see which companies still have open slots
This is the query i'm trying but it's giving me the wrong results.
select
name,
slots,
(select count(*) from persons) as persons
from companies
where city_id = 3
group by companies.id
This should give me a table with the slots, and the amount of personsfilled for that company in the persons table, but it's returning the total amount of persons every time.
This is the result
Thank you!
Like #JoeTaras said, you need to join persons and companies to be able to tell/count which persons belong to which company. If you don't join them somehow, companies and persons will be treated and counted independently which is normally not very useful.
A different sub-query could indeed be used, but it's not quite how 'you do it', and will probably be less performant than the straight-forward join.
Example:
select
companies.id
companies.name,
companies.slots,
count(persons.id)
from companies
left outer join persons on companies.id = persons. ...
where companies.city_id = 3
group by companies.id, companies.name, companies.slots
I have 3 tables:
Orders
- id
- customer_id
Details
- id
- order_id
- product_id
- ordered_qty
Parcels
- id
- detail_id
- batch_code
- picked_qty
Orders have multiple Details rows, a detail row per product.
A detail row has multiple parcels, as 10'000 ordered qty may come from 6 different batches, so goods from batches are packed and shipped separately. The picked quantity put in each parcel for a detail row should then be the same as the ordered_qty.
... hope that makes sense.
Im struggling to write a query to provide summary information of all of this.
I need to Group By customer_id to provide a row of data per customer.
That row should contain
Their total number of orders
Their total ordered_qty of goods across all orders
Their total picked_qty of goods across all orders
I can get the first one with:
SELECT customer_id, COUNT(*) as number_of_orders
FROM Orders
GROUP BY Orders.customer_id
But when I LEFT JOIN the other two tables and add the
SELECT ..... SUM(Details.ordered_qty) AS total_qty_ordered,
SUM(Parcels.picked_qty) AS total_qty_picked
.. then I get results that dont seem to add up for the quantities, and the COUNT(*) seems to include the additional lines from the JOIN which obviously then isn't giving me the number of Orders anymore.
Not sure what to try next.
===== EDIT =======
Here's the query I tried:
SELECT
customer_id,
COUNT(*) as number_of_orders,
SUM(Details.ordered_qty) AS total_qty_ordered,
SUM(Parcels.picked_qty) AS total_qty_picked
FROM Orders
LEFT JOIN Details ON Details.order_id=Order.id
LEFT JOIN Parcels ON Parcels.detail_id=Detail.id
GROUP BY Orders.customer_id
try COUNT(distinct Orders.order_id) as number_of_orders,
as in
SELECT
customer_id,
COUNT(distinct Orders.order_id) as number_of_orders,
SUM(Details.ordered_qty) AS total_qty_ordered,
(select SUM(Parcels.picked_qty)
FROM Parcels WHERE Parcels.detail_id=Detail.id ) AS total_qty_picked
FROM Orders
LEFT JOIN Details ON Details.order_id=Order.id
GROUP BY Orders.customer_id
EDIT: added an other select with subselect
Is there any particular reason you feel the need to combine all these in one query? Simplify by breaking it up in to separate queries, and if you want a single call to get the results, put the queries in a stored procedure, using temp tables.