MySql LEFT JOIN with COUNT - mysql

I have two tables, customers and sales. I want to count sales for each customer and create a table of sales per month for each store.
I would like to produce something like;
------------------------------
month | customers | sales |
------------------------------
1/2013 | 5 | 2 |
2/2013 | 21 | 9 |
3/2013 | 14 | 4 |
4/2013 | 9 | 3 |
but I am having trouble getting the sales count to be correct when using the following;
SELECT CONCAT(MONTH(c.added), '/', YEAR(c.added)), count(c.id), count(s.id)
FROM customers c
LEFT JOIN sales s
ON s.customer_id = c.id AND MONTH(c.added) = MONTH(s.added) AND YEAR(c.added) = YEAR(s.added)
WHERE c.store_id = 1
GROUP BY YEAR(c.added), MONTH(c.added);
Customers table;
-------------------------------
id | store_id | added |
-------------------------------
1 | 1 |2013-02-01 |
2 | 1 |2013-02-02 |
3 | 1 |2013-03-16 |
sales table;
---------------------------------
id | added | customer_id |
---------------------------------
1 | 2013-02-18 | 3 |
2 | 2013-03-02 | 2 |
3 | 2013-03-16 | 3 |
Can anyone help here?
thanks

(Updated) The existing query will only count sales made in the same month that the customer was added. Try this, instead:
SELECT CONCAT(MONTH(sq.added), '/', YEAR(sq.added)) month_year,
sum(sq.customer_count),
sum(sq.sales_count)
FROM (select s.added, 0 customer_count, 1 sales_count
from customers c
JOIN sales s ON s.customer_id = c.id
WHERE c.store_id = 1
union all
select added, 1 customer_count, 0 sales_count
from customers
WHERE store_id = 1) sq
GROUP BY YEAR(sq.added), MONTH(sq.added);

SELECT c.* , s.sales_count<br>
FROM customers c<br>
LEFT JOIN (SELECT customer_id, count(id) as sales_count FROM sales GROUP BY customer_id) s on c.id=s.customer_id<br>
WHERE c.store_id = 1<br>

Related

How to calculate max values of groups?

I have a table like so (I'm not sure how to format tables)
Category / Products / Purchases
1 | A | 12
1 | B | 13
1 | C | 11
2 | A | 1
2 | B | 2
2 | C | 3
Expected output:
1 | B | 13
2 | C | 3
However I keep on getting
1 | A | 13
2 | A | 3
ie. It just selects the first occurrence of the second column.
Here is my code:
SELECT Category, Products, MAX(Purchases) FROM myTable GROUP BY Category;
Use filtering in the where clause:
select t.*
from t
where t.purchases = (select max(t2.purchases) from t t2 where t2.category = t.category);
With NOT EXISTS:
select m.* from myTable m
where not exists (
select 1 from myTable
where category = m.category and purchases > m.purchases
)
See the demo.
Results:
| Category | Products | Purchases |
| -------- | -------- | --------- |
| 1 | B | 13 |
| 2 | C | 3 |
You can use row_number() to identify max purchase for each group or replace rownumber() to rank() if there are ties of max purchases for each group
Select Category, Products,
Purchases from (Select Category,
Products,
Purchases,
row_number() over (partition by
category, products order by
purchases desc) rn from table) t
where t.rn=1
)

Get SUM of two fields in 2 different related tables

I'd like to get the SUM of the amount column in two related tables.
Invoices Table:
-----------------------------------------
| id | student_id | created | updated |
-----------------------------------------
| 5 | 25 | date | date |
-----------------------------------------
Invoice Items Table:
------------------------------
| id | invoice_id | amount |
------------------------------
| 1 | 5 | 250 |
------------------------------
| 2 | 5 | 100 |
------------------------------
| 3 | 5 | 40 |
------------------------------
Payments Table:
------------------------------
| id | invoice_id | amount |
------------------------------
| 1 | 5 | 100 |
------------------------------
| 2 | 5 | 290 |
------------------------------
Desired Output:
--------------------------------------
| id | invoiceTotal | paymentTotal |
--------------------------------------
| 1 | 390 | 390 |
--------------------------------------
The query I've tried
SELECT
i.id,
sum(ii.amount) as invoiceTotal,
sum(p.amount) as paymentTotal
FROM
invoices i
LEFT JOIN
invoice_items ii ON i.id = ii.invoice_id
LEFT JOIN
payments p ON i.id = p.invoice_id
WHERE
i.student_id = '25'
GROUP BY
i.id
What this seems to do is calculate the sum of the payments properly but the invoice_items.amount appears to have been duplicated by 6 (which is the number of payments there are).
I have read similar questions on SO here and here but the examples are so much more complex than what I'm trying to do and I can't figure out what to put where.
The join causes a problem with cartesian products. If a student has multiple invoice items and payments, then the totals will be wrong.
One approach that works best for all invoices is a union all/group by approach:
select i.id, sum(invoiceTotal) as invoiceTotal, sum(paymentTotal) as paymentTotal
from ((select i.id, 0 as invoiceTotal, 0 as paymentTotal
from invoices i
) union all
(select ii.invoiceId, sum(ii.amount) as invoiceTotal, NULL
from invoiceitems ii
group by ii.invoiceId
) union all
(select p.invoiceId, 0, sum(p.amount) as paymentTotal
from payments p
group by p.invoiceId
)
) iip
group by id;
For a single student, I would recommend correlated subqueries:
select i.id,
(select sum(ii.amount)
from invoiceitems ii
where ii.invoiceid = i.id
) as totalAmount,
(select sum(p.amount)
from payment p
where p.invoiceid = i.id
) as paymentAmount
from invoices i
where i.studentid = 25;

How to SUM column in MySQL left join

So i have table cont_selling
---------------------------------
cont_selling_id | date |
---------------------------------
1 | 2015-05-24 |
2 | 2015-06-06 |
---------------------------------
table 02 cont_sold
----------------------------------------------------
cont_sold_id | cont_selling_id | price |
---------------------------------------------------
1 | 1 | 10 |
2 | 1 | 10 |
3 | 1 | 30 |
4 | 2 | 20 |
5 | 2 | 10 |
--------------------------------------------------
and table 03 payment
----------------------------------------------
payment_id | cont_selling_id | paid |
-----------------------------------------------
1 | 1 | 10 |
2 | 2 | 10 |
3 | 1 | 20 |
4 | 1 | 10 |
5 | 2 | 10 |
-----------------------------------------------
now i need to SELECT table based on
now i want to merge all these three tables based on cont_selling table cont_selling_id column
and want to SUM cont_sold table price column and payment table paid column
this is what i want to do
expecting output
---------------------------------------------
cont_selling_id | price | paid |
---------------------------------------------
1 | 50 | 40 |
2 | 30 | 20 |
---------------------------------------------
so i tried like this in mysql query but it give wrong sum result
SELECT
SUM(Z.price) as total,
SUM(P.amount) as paid
FROM cont_selling S
LEFT JOIN cont_sold Z
ON S.cont_selling_id = Z.cont_selling_id
LEFT JOIN payment P
ON S.cont_selling_id = P.cont_selling_id
GROUP BY S.cont_selling_id
for this above query i m getting output like this
---------------------------------------------
cont_selling_id | price | paid |
---------------------------------------------
1 | 150 | 40 |
2 | 60 | 120 |
---------------------------------------------
Here how you can do it using the aggegare part into inner queries and then join
select
cs.cont_selling_id,
price,
paid
from cont_selling cs
left join(
select sum(price) as price , cont_selling_id from cont_sold
group by cont_selling_id
)x on x.cont_selling_id = cs.cont_selling_id,
left join(
select sum(paid) as paid , cont_selling_id from payment
group by cont_selling_id
)y
on y.cont_selling_id = cs.cont_selling_id;
You should make two different queries with SUM and then combine them to get the desired result:
SELECT T1.cont_selling_id,T1.price,T2.paid
FROM
(SELECT c.cont_selling_id,SUM(cs.price) as price
FROM cont_selling c LEFT JOIN
cont_sold cs ON c.cont_selling_id=cs.cont_selling_id
GROUP BY c.cont_selling_id) as T1 JOIN
(SELECT c.cont_selling_id,SUM(p.paid) as paid
FROM cont_selling c LEFT JOIN
payment p ON p.cont_selling_id=c.cont_selling_id
GROUP BY c.cont_selling_id) as T2 ON T1.cont_selling_id=T2.cont_selling_id
Result:
cont_selling_id price paid
----------------------------
1 50 40
2 30 20
Sample result in SQL Fiddle.
This untested query should work:
with a as(select cont_selling_id , sum(price) as totalprice from cont_sold group by cont_selling_id),
with a as(select cont_selling_id , sum(paid) as totalpaid from payment group by cont_selling_id),
select c.cont_selling_id , totalprice, totalpaid from cont_selling c left join a.count_selling_id = c.count_selling_id
left join b.count_selling_id = c.count_selling_id
You have to create temporary tables, because there is no dependency between your table for price and paid.

Join on same column name

Hello there I want to get data from two tables that share same column name. My table structure are
Table patients
---------------------------------------
| id | affiliate_id | somecolumn |
---------------------------------------
| 1 | 8 | abc |
---------------------------------------
| 2 | 8 | abc |
---------------------------------------
| 3 | 9 | abc |
---------------------------------------
Table Leads
---------------------------------------
| id | affiliate_id | someothern |
---------------------------------------
| 1 | 8 | xyz |
---------------------------------------
| 2 | 8 | xyz |
---------------------------------------
| 3 | 3 | xyz |
---------------------------------------
Now my requirement was to get COUNT(ID) from both tables in a single query. I want result like
----------------------------------------------------
| affiliate_id | total_patients | total_leads |
----------------------------------------------------
| 8 | 2 | 2 |
----------------------------------------------------
| 9 | 1 | 0 |
----------------------------------------------------
| 3 | 0 | 1 |
----------------------------------------------------
I wrote following query
SELECT `p`.`affiliate_id`, COUNT(p.id) AS `total_patients`,
COUNT(cpl.id) AS `total_leads`
FROM `patients` AS `p`
INNER JOIN `leads` AS `cpl` ON p.affiliate_id =cpl.affiliate_id
GROUP BY `p`.`affiliate_id`
But I am not getting result . This query results giving only one affiliate with same number of total_patients and total_leads
The problem is that you need to get a list of the distinct affiliate_id first and then join to your other tables to get the result:
select a.affiliate_id,
count(distinct p.id) total_patients,
count(distinct l.id) total_leads
from
(
select affiliate_id
from patients
union
select affiliate_id
from leads
) a
left join patients p
on a.affiliate_id = p.affiliate_id
left join leads l
on a.affiliate_id = l.affiliate_id
group by a.affiliate_id;
See SQL Fiddle with Demo
Two ways:
Select l.affiliate_id ,
count(distinct p.id) patientCount,
count(distinct l.id) LeadCOunt
From patients p Join leads l
On l.affiliate_id = p.Affiliate_id
Group By l.affiliate_id
or, (assuming affiliates are in their own table somewhere)
Select Affiliate_id,
(Select Count(*) From Patients
Where Affiliate_id = a.Affiliate_id) patientCount,
(Select Count(*) From Leads
Where Affiliate_id = a.Affiliate_id) LeadCount
From affiliates a

Add column from another table, but not affect count()

I have already a query with multiple JOINs, simple list of reservations
SELECT reservation.reservation_id, customer.customer_id, customer.name, count(ordered_services.reservation_id) AS num_of_ordered_services
FROM reservations
JOIN customers ON reservations.customer_id = customer.customer_id
LEFT JOIN ordered_services ON reservations.reservation_id = ordered_services.reservation_id
GROUP BY reservation.reservation_id, customer.customer_id, customer.name
ORDER BY reservation.reservation_id
which outputs something like
reservation_id | customer_id | name | num_of_ordered_services
1 | 1909091202 | John | 2
2 | 2512541508 | Jane | 3
I would like to add another column with information about payment, but simple JOIN, LEFT JOIN interferes with existing count() column. Like
SELECT reservation.reservation_id, count(payments.reservation_id) AS num_of_payments
FROM reservations
LEFT JOIN payments ON reservations.reservation_id = payments.reservation_id
GROUP BY reservation.reservation_id
ORDER BY reservation.reservation_id
reservation_id | num_of_payments
1 | 0
2 | 2
but in both a single result. How to achieve this?
PS: num_of_payments is not necessary, I only need to know if the payment for certain reservation exists or not (1, 0).
Thank you
tbl structure, nothing special:
reservations
reservation_id | customer_id | added
1 | 1909091202 | 2011-11-04 02:37:28
2 | 2512541508 | 2011-11-04 14:27:01
customers
customer_id | name | personal information columns ...
1909091202 | John | | |
2512541508 | Jane | | |
... | ... | | |
payments
payment_id | reservation_id | customer_id | total | added
1 | 2 | 1909091202 | 199 | 2011-11-04 02:37:28
2 | 2 | 2512541508 | 50 | 2011-11-04 14:27:01
You could use a subselect for the additional field.
SELECT reservation.reservation_id, customer.customer_id, customer.name,
count(ordered_services.reservation_id) AS num_of_ordered_services,
(SELECT count(*) FROM payments WHERE reservation.reservation_id=payments.reservation_id) AS num_of_payments
FROM reservations
JOIN customers ON reservations.customer_id = customer.customer_id
LEFT JOIN ordered_services ON reservations.reservation_id = ordered_services.reservation_id
GROUP BY reservation.reservation_id, customer.customer_id, customer.name
ORDER BY reservation.reservation_id
Something like the following should work:
select
reservation.reservation_id,
(case when exists (select * from payments p1 where p1.reservation_id = reservation.reservation_id) then 1 else 0 end) as one_or_many_payments_made
from reservation
GROUP BY reservation.reservation_id
ORDER BY reservation.reservation_id
But without your data, there is some guesswork here.