This question already has answers here:
SQL select only rows with max value on a column [duplicate]
(27 answers)
Get records with max value for each group of grouped SQL results
(19 answers)
Closed 4 years ago.
I want to join these two tables, showing the most recent due date for every client:
Table "clients":
| id_client | name |
|-----------|------------|
| 1 | Customer 1 |
| 2 | Customer 2 |
| 3 | Customer 3 |
Table "invoices" (FK id_client):
| id_invoice | id_client | due_date | payment_frequency |
|------------|-----------|------------|-------------------|
| 1 | 1 | 2018-11-30 | monthly |
| 2 | 1 | 2018-12-30 | monthly |
| 3 | 2 | 2019-01-01 | quarterly |
| 4 | 2 | 2019-01-01 | quarterly |
Desired result:
| id_client | name | due_date | payment_frequency |
|-----------|------------|------------|-------------------|
| 1 | Customer 1 | 2018-12-30 | monthly |
| 2 | Customer 2 | 2019-01-01 | quarterly |
| 3 | Customer 3 | (null) | (null) |
Details:
It should return all clients records, even those with no invoices (null).
Some customers have more than one invoice that due on the same date (id_invoice 3 and 4 in this example), but only one record should be returned.
I was able to make it work through the following query:
SELECT
c.id_client,c.name,
(SELECT due_date FROM invoices WHERE id_client=c.id_client ORDER BY due_date DESC LIMIT 1) AS due_date,
(SELECT payment_frequency FROM invoices WHERE id_client=c.id_client ORDER BY due_date DESC LIMIT 1) AS payment_frequency
FROM
clients AS c
I think there are more elegant and better-performing ways, through joins. Can you give me your suggestion please?
This table structure, data and query at Fiddle
Ps. Despite the question is marked as a duplicate, other questions and answers do not solve this case.
Please check this out
select
c.id_client,
c.name,
max(i.due_date) due_date,
max(i.payment_frequency) payment_frequency
from clients c
left outer join invoices i
on c.id_client = i.id_client
group by
c.id_client,
c.name
Edit: Please check my edited answer
select
c.id_client,
c.name,
i.due_date due_date,
i.payment_frequency payment_frequency
from clients c
left outer join invoices i
on c.id_client = i.id_client
where due_date is null or due_date = (select max(due_date) from invoices where id_client = i.id_client)
group by c.id_client, c.name, i.due_date, i.payment_frequency
Related
I'm having a hard time setting up a query(select). Database is not my specialty, so I'm turning to the experts. Let me show what I need.
----companies--- ----company_server----- -----servers---- -----print------------------------
| id | name | | company | server | | id | name | | id |page|copy | date |server
|----|-------- | |---------|----------| |----|-------- | |----|----|-----|-------------
| 1 | Company1 |1--N| 1 | 1 |N*--1| 1 | Server1 |1--N| 1 | 2 | 3 | 2020-1-11 | 1
| 2 | Company2 | | 2 | 1 | | 2 | Server2 | | 2 | 1 | 6 | 2020-1-12 | 3
| 3 | Company3 | | 3 | 2 | | 3 | Server3 | | 3 | 4 | 5 | 2020-1-13 | 4
| 3 | 3 | | 4 | Server4 | | 4 | 5 | 3 | 2020-1-15 | 2
| 5 | 3 | 4 | 2020-1-15 | 4
| 6 | 1 | 2 | 2020-1-16 | 3
| 7 | 2 | 2 | 2020-1-16 | 4
What I need?
Example where date between CAST(2020-1-12 AS DATE) AND CAST(2020-1-15 AS DATE) group by servers.id
| companies | server | sum | percent
------------------------------------------------------------------------------------
| company1,company2 | server1 | sum(page*copy) = 0 or null | 0 or NULL
| company3 | server2 | sum(page*copy) = 15 | 28.30
| company3 | server3 | sum(page*copy) = 6 | 11.32
| NULL | server4 | sum(page*copy) = 32 | 60.38
Few notes:
I need this query for MYSQL;
Every Company is linked to at least one server.
I need result grouped by server. So, every company linked to that server must be concatenated by a comma.
If the company has not yet been registered, the value null should be presented.
The sum (page * copie) must be presented as zero or null (I don't care) in the case that there was no printing in the date range.
The percentage should be calculated according to the date range entered and not with all records in the database.
The field date is stored as MYSQL DATE.
Experts, I thank you in advance for your help. I currently solve this problem with at least 03 queries to the database, but I have a conviction that I could do it with just one query.
Added a fiddle. Sorry. Im still learing how to use this.
https://www.db-fiddle.com/f/dXej7QCPe9iDopfYd1SfVh/2
Follows the query that more or less represents how far I had arrived. Notice that in the middle of the way 'server4' disappeared because there are no values for it in print in the period searched for him and I am in possession of the total of the period but I cannot calculate the percentage.
i'm stuck
select
*
from
(select
sum(p.copy * p.page) as sum1,
s.name as s_name,
s.id as s_id
from
print p
join servers s on s.id = p.server
where p.date between cast('2020-1-12' as date) and cast('2020-1-15' as date)
group by s.id) as t1
join company_server cs on cs.server = t1.s_id
right join companies c on c.id = cs.company
cross join(
select
sum(p1.copy * p1.page) sum2
from
print p1
where p1.date between cast('2020-1-12' as date) and cast('2020-1-15' as date)
) as c;
I did this query before you add fiddle, so may be name of column of mine is not same as you. Anyway, this is my solution, hope it help you.
select group_concat(c.name separator ',') as name_company,
ss.name,
sum_print as sum,
(sum_print/total) *100 as percentage
from companies c
inner join company_server cs on c.id = cs.company
right join servers ss on ss.id = cs.id
left join
(
select server,sum(page*copy) as sum_print, date from print
where date between CAST('2020-1-12' AS DATE) AND CAST('2020-1-15' AS DATE)
group by server
) tmp on tmp.server = ss.id
cross join
(select sum(page*copy) as total from print where date between CAST('2020-1-12' AS DATE) AND CAST('2020-1-15' AS DATE)) tmp2
group by id
Group and concat by comma, using GROUP_CONCAT .
You can reference this image for JOIN clause.
https://i.stack.imgur.com/6cioZ.png
This question already has answers here:
How can I SELECT rows with MAX(Column value), PARTITION by another column in MYSQL?
(22 answers)
Closed 4 years ago.
I have 2 tables:
manifests
id | customer | paid_order | price | payment_method
paid_orders
id | paid
JOIN paid_orders ON manifests.paid_order = paid_order_id
Let's assume this scenario:
There are 2 same customer but has different payment_method.
customer | paid_order | price | payment_method | paid |
1 | 1 | 200 | 0 | 200 |
1 | NULL | 100 | 1 | NULL |
2 | NULL | 150 | 1 | NULL |
I only want to GROUP BY customer but also PICK only the payment_method of 0 only if there are two same customer.
Expected result:
customer | paid_order | price | payment_method | paid |
1 | 1 | 200 | 0 | 200 |
2 | NULL | 150 | 1 | NULL |
One approach would be to always select the record from one, or possibly more, customer records where the payment_method has the minimum value:
SELECT m1.*
FROM manifest m1
INNER JOIN
(
SELECT customer, MIN(payment_method) AS min_payment_method
FROM manifest
GROUP BY customer
) m2
ON m1.customer = m2.customer AND m1.payment_method = m2.min_payment_method;
This logic should work, because if a payment_method of zero be present, then this record would be targeted. Otherwise, the one value record would be targeted.
I have two tables, one that store product information and one that stores reviews for the products.
I am now trying to get the number of reviews submitted for the products between two dates but for some reason I get the same results regardless of the dates i put.
This is my query:
SELECT
productName,
COUNT(*) as `count`,
avg(rating) as `rating`
FROM `Reviews`
LEFT JOIN `Products` using(`productID`)
WHERE `date` BETWEEN '2015-07-20' AND '2015-07-30'
GROUP BY
`productName`
ORDER BY `count` DESC, `rating` DESC;
This returns:
+------------+---------------------+
| productName| count|rating |
+------------+------+--------------+
| productA | 23 | 4.3333333 |
| productB | 17 | 4.25 |
| productC | 10 | 3.5 |
+------------+---------------------+
Products table:
+---------+-------------+
|productID | productName|
+---------+-------------+
| 1 | productA |
| 2 | productB |
| 3 | productC |
+---------+-------------+
Reviews table
+---------+-----------+--------+---------------------+
|reviewID | productID | rating | date |
+---------+-----------+--------+---------------------+
| 1 | 1 | 4.5 | 2015-07-27 17:47:01|
| 2 | 1 | 3.5 | 2015-07-27 18:54:22|
| 3 | 3 | 2 | 2015-07-28 13:28:37|
| 4 | 1 | 5 | 2015-07-28 18:33:14|
| 5 | 2 | 1.5 | 2015-07-29 11:58:17|
| 6 | 2 | 3.5 | 2015-07-30 15:04:25|
| 7 | 2 | 2.5 | 2015-07-30 18:11:11|
| 8 | 1 | 3 | 2015-07-30 18:26:23|
| 9 | 1 | 3 | 2015-07-30 21:35:05|
| 10 | 1 | 4.5 | 2015-07-31 14:25:47|
| 11 | 3 | 0.5 | 2015-07-31 14:47:48|
+---------+-----------+--------+---------------------+
when I put two random dates that I do know for sure they not on the date column, I will still get the same results. Even when I want to retrieve records only on a certain day, I get the same results.
You should not use left join, because by doing so you retrieve all the data from one table. What you should use is something like :
select
productName,
count(*) as `count`,
avg(rating) as `rating`
from
products p,
reviews r
where
p.productID = r.productID
and `date` between '2015-07-20' and '2015-07-30'
group by productName
order by count desc, rating desc;
If the result, given your sample data, that you're looking for is:
| productName | count | rating |
|-------------|-------|--------|
| productA | 5 | 4 |
| productB | 3 | 3 |
| productC | 1 | 2 |
This is the count and average of reviews made on any date between 2015-07-20 and 2015-07-30 inclusive.
Then the there are two issues with your query. First, you need to change the join to a inner join instead of a left join, but more importantly you need to change the date condition as you are currently excluding reviews that fall on the last date on the range, but after midnight.
This happens because your between clause compares datetime values with date values so the comparison ends up being date between '2015-07-20 00:00:00' and '2015-07-30 00:00:00' which clearly excludes some dates at the end.
The fix is to either change the date condition so that the end is a day later:
where date >= '2015-07-20' and date < '2015-07-31'
or cast the date column to a date value, which will remove the time part:
where date(date) between '2015-07-20' and '2015-07-30'
Sample SQL Fiddle
You are using a LEFT JOIN between your reviews and your products tables. This will result in all the rows of reviews being shown with some rows having all product columns left empty.
You should use INNER JOIN, as this will filter only the wanted results.
(In the end I can only guess, since I don't even know which column belongs to which table ...)
The full query (very similar to Angelo Giannis's solution):
select
productName,
count(*) as `count`,
avg(rating) as `rating`
from
products INNER JOIN reviews USING(productId)
where date between '2015-07-20' and '2015-07-30'
group by productName
order by count desc, rating desc;
Here a fiddle with my and Angelo's solution (they both work).
I'd like a little help here.
I'm building a database in MySQL where I will have a bunch of different activities. Each activity is part of a list.
So, I have the following tables on my database.
List
id
name
Activity
id
name
idList (FK to List)
I also want to know when each activity is finished (you can finish the same activity many times). To accomplish that, I have another table:
History
date
idActivity (FK to activity)
When the user finishes an activity, I add the id of this activity and the current time the activity was finished, to the History table.
I want to get the entire list with the date it was finished. When an activity has not been finished, I want it to show the date as null.
But, getting the list just once is easy. A simple Left Outer Join will do the trick. My issue here is that I want to get the ENTIRE list everytime a date appears on the history table.
This is what I'm looking for:
List:
id | name
1 | list1
Activity:
id | name | idList
1 | Activity1 | 1
2 | Activity2 | 1
3 | Activity3 | 1
4 | Activity4 | 1
5 | Activity5 | 1
6 | Activity6 | 1
History:
date | idActivity
17/07/14 | 1
17/07/14 | 3
17/07/14 | 4
17/07/14 | 6
16/07/14 | 2
16/07/14 | 3
16/07/14 | 5
Expected Result:
idActivity | idList | activityName | date
1 | 1 | Activity1 | 17/07/14
2 | 1 | Activity2 | NULL
3 | 1 | Activity3 | 17/07/14
4 | 1 | Activity4 | 17/07/14
5 | 1 | Activity5 | NULL
6 | 1 | Activity6 | 17/07/14
1 | 1 | Activity1 | NULL
2 | 1 | Activity2 | 16/07/14
3 | 1 | Activity3 | 16/07/14
4 | 1 | Activity4 | NULL
5 | 1 | Activity5 | 16/07/14
6 | 1 | Activity6 | NULL
The "trick" is to use a CROSS JOIN (or semi-cross join) operation with a distinct list of dates from the history table, to produce the set of rows you want to return.
Then a LEFT JOIN (outer join) to the history table to find the matching history rows.
Something like this:
SELECT a.id AS idActivity
, a.idList AS idList
, a.name AS activityName
, h.date AS `date`
FROM activity a
CROSS
JOIN ( SELECT s.date
FROM history s
GROUP BY s.date
) r
LEFT
JOIN history h
ON h.idActivity = a.id
AND h.date = r.date
ORDER
BY r.date
, a.id
That query gets the six rows from activity, and two rows (distinct values of date) from history (inline view aliased as r). The CROSS JOIN operation matches each of the six rows with each of the two rows, to produce a Cartesian product of 12 rows.
To get the rows returned in the specified order, we order by date, and then by activity.id.
I would like to ask a quick question regarding a mysql query.
I have a table named trans :
+----+---------------------+------+-------+----------+----------+
| ID | Date | User | PCNum | Customer | trans_In |
+----+---------------------+------+-------+----------+----------+
| 8 | 2013-01-23 16:24:10 | test | PC2 | George | 10 |
| 9 | 2013-01-23 16:27:22 | test | PC2 | Nick | 0 |
| 10 | 2013-01-24 16:28:48 | test | PC2 | Ted | 10 |
| 11 | 2013-01-25 16:36:40 | test | PC2 | Danny | 10 |
+----+---------------------+------+-------+----------+----------+
and another named customers :
+----+---------+-----------+
| ID | Name | Surname |
+----+---------+-----------+
| 1 | George | |
| 2 | Nick | |
| 3 | Ted | |
| 4 | Danny | |
| 5 | Alex | |
| 6 | Mike | |
.
.
.
.
+----+---------+-----------+
I want to view the sum of trans_in column for specific customers in a date range BUT ALSO include in the result set, those customers that haven't got any records in the selected date range. Their sum of trans_in could appear as NULL or 0 it doesn't matter...
I have the following query :
SELECT
`Date`,
Customer,
SUM(trans_in) AS 'input'
FROM trans
WHERE Customer IN('George','Nick','Ted','Danny')
AND `Date` >= '2013-01-24'
GROUP BY Customer
ORDER BY input DESC;
But this will only return the sum for 'Ted' and 'Danny' because they only have transactions after the 24th of January...
How can i include all the customers that are inside the WHERE IN (...) function, even those who have no transactions in the selected date range??
I suppose i'll have to join them somehow with the customers table but i cannot figure out how.
Thanks in advance!!
:)
In order to include all records from one table without matching records in another, you have to use a LEFT JOIN.
SELECT
t.`Date`,
c.name,
SUM(t.trans_in) AS 'input'
FROM customers c LEFT JOIN trans t ON (c.name = t.Customer AND t.`Date` >= '2013-01-24')
WHERE c.name IN('George','Nick','Ted','Danny')
GROUP BY c.name
ORDER BY input DESC;
Of course, I would mention that you should be referencing customer by ID, and not by name in your related table. Your current setup leads to information duplication. If the customer changes their name, you now have to update all related records in the trans table instead of just in the customer table.
try this
SELECT
`Date`,
Customer,
SUM(trans_in) AS 'input'
FROM trans
inner join customers
on customers.Name = trans.Customer
WHERE Customer IN('George','Nick','Ted','Danny')
GROUP BY Customer
ORDER BY input DESC;