I keep getting error code #1241. I have been looking to find an answer but I can't find an answer that helped me.
Here is my code:
SELECT name, address, city, phone
FROM customer
WHERE customer.ID IN (
SELECT customer.ID, COUNT(*) AS amount_reservations
FROM customer, (
SELECT ID
FROM customer, reservations
WHERE rent_time = 'weekend' AND
ID = customer_ID
) AS foo
WHERE customer.ID = foo.ID
GROUP BY customer.ID
HAVING amount_reservations > 1
)
The subquery SELECT customer.ID, COUNT(*) AS amount_reservations should have a SINGLE column, not two.
Change it as:
SELECT name, address, city, phone
FROM customer
WHERE customer.ID IN (
SELECT customer.ID
FROM customer, (
SELECT ID FROM customer, reservations
WHERE rent_time = 'weekend' AND ID = customer_ID
) AS foo
WHERE customer.ID = foo.ID
GROUP BY customer.ID HAVING count(*) > 1
)
I'd highly recommend rewriting your query. Remove the subqueries -- they aren't needed. Then use explicit joins instead of commas.
select c.id, c.name, c.address, c.city, c.phone
from customer c
join reservations r on c.id = r.customer_id
where r.rent_time = 'weekend'
group by c.id, c.name, c.address, c.city, c.phone
having count(*) > 1
If you want to use in, you can radically simplify the query:
SELECT c.name, c.address, c.city, c.phone
FROM customer c
WHERE c.ID IN (SELECT r.customer_id
FROM reservations r
WHERE r.rent_time = 'weekend'
GROUP BY r.customer_id
HAVING COUNT(*) > 1
) ;
Notes:
Never use commas in the FROM clause. Always use proper, explicit, standard JOIN syntax.
Use table aliases and qualified column names for all column references.
You don't need a JOIN in the subquery, because you have the customer id in the reservations table.
Related
I have this schema here, and I need to find the name of the customer with the highest total amount for the orders. I have a SQL query here:
SELECT Name
FROM (SELECT Name, SUM(Amount) AS Total
FROM customer JOIN orders ON cust_id = ID
GROUP BY Name) AS Totals
WHERE Total = (SELECT MAX(Total)
FROM (SELECT Name, SUM(Amount) AS Total
FROM customer JOIN orders ON cust_id = ID
GROUP BY Name) AS X);
But this is very inefficient as it creates the same table twice. Is there any more efficient way to get the name?
If you want customer with the greatest total mount, then you can just join, order by and limit:
select c.name
from customer c
inner join orders o on o.cust_id = c.id
group by c.id, c.name
order by sum(o.amount) desc
limit 1
Note that this does not handle possible top ties. For this, you need a little more code. Instead of ordering, you would typically filter with a having clause:
select c.name
from customer c
inner join orders o on o.cust_id = c.id
group by c.id, c.name
having sum(o.amount) = (
select sum(o1.amount)
from orders o1
group by cust_id
order by sum(o1.amount) desc
limit 1
)
Finally: if you are running MySQL 8.0, this is simpler done with window function rank():
select name
from (
select c.name, rank() over(order by sum(o.amount) desc) rn
from customer c
inner join orders o on o.cust_id = c.id
group by c.id, c.name
) t
where rn = 1
I need to write a query to find the youngest customer who bought atleast 1 product
Here is the data:
CUSTOMER:
ORDER_DETAIL:
This is my query so far:
SELECT c.CUSTOMERID, c.age, c.name
from (
SELECT CUSTOMERID, COUNT(ORDERID) as "totalOrder"
FROM FACEBOOK_ORDER_DETAIL
GROUP BY CUSTOMERID
HAVING COUNT(ORDERID) >=1) AS tbl
LEFT JOIN FACEBOOK_CUSTOMER c on c.CUSTOMERID = tbl.CUSTOMERID
order by c.age ;
However, above query gives me
But I need the list of customers with the minimum age.
If you really only want a single youngest customer, even should there be a tie, then use LIMIT:
SELECT c.CUSTOMERID, c.age, c.name
FROM CUSTOMER c
INNER JOIN FACEBOOK_ORDER_DETAIL o
ON c.CUSTOMERID = c.CUSTOMERID
ORDER BY
c.age
LIMIT 1;
This should work because if a customer joins to the order details table, it implies that he had at least one order.
If instead you want to find all youngest customers, including all ties, then a nice way to handle this uses the RANK analytic function:
SELECT DISTINCT CUSTOMERID, age, name
FROM
(
SELECT c.CUSTOMERID, c.age, c.name, RANK() OVER (ORDER BY c.age) rnk
FROM CUSTOMER c
INNER JOIN FACEBOOK_ORDER_DETAIL o
ON c.CUSTOMERID = o.CUSTOMERID
) t
WHERE rnk = 1;
Demo
For earlier versions of MySQL, we can use a subquery as a workaround for not having RANK:
SELECT DISTINCT c.CUSTOMERID, c.age, c.name
FROM CUSTOMER c
INNER JOIN FACEBOOK_ORDER_DETAIL o
ON c.CUSTOMERID = c.CUSTOMERID
WHERE c.age = (SELECT MIN(t1.age)
FROM CUSTOMER t1
INNER JOIN FACEBOOK_ORDER_DETAIL t2
ON t1.CUSTOMERID = t2.CUSTOMERID);
Demo
You only want columns from customers, so I would phrase this as:
select c.*
from (select c.*,
rank() over (order by age) as seqnum
from customers c
where exists (select 1
from facebook_order_detail fod
where fod.customerid = c.customerid
)
) c
where seqnum = 1;
In particular, this requires no duplicate elimination or aggregation, so it should be faster. And it can use an index on face_book_details(customerid) and also perhaps on customers(age, customerid).
I have these tables : customers, customer_invoices, customer_invoice_details, each customer has many invoices, and each invoice has many details.
The customer with the ID 574413 has these invoices :
select customer_invoices.customer_id,
customer_invoices.id,
customer_invoices.total_price
from customer_invoices
where customer_invoices.customer_id = 574413;
result :
customer_id invoice_id total_price
574413 662146 700.00
574413 662147 250.00
each invoice here has two details (or invoice lines) :
first invoice 662146:
select customer_invoice_details.id as detail_id,
customer_invoice_details.customer_invoice_id as invoice_id,
customer_invoice_details.total_price as detail_total_price
from customer_invoice_details
where customer_invoice_details.customer_invoice_id = 662146;
result :
detail_id invoice_id detail_total_price
722291 662146 500.00
722292 662146 200.00
second invoice 662147 :
select customer_invoice_details.id as detail_id,
customer_invoice_details.customer_invoice_id as invoice_id,
customer_invoice_details.total_price as detail_total_price
from customer_invoice_details
where customer_invoice_details.customer_invoice_id = 662147;
result :
detail_id invoice_id detail_total_price
722293 662147 100.00
722294 662147 150.00
I have a problem with this query :
select customers.id as customerID,
customers.last_name,
customers.first_name,
SUM(customer_invoices.total_price) as invoice_total,
SUM(customer_invoice_details.total_price) as details_total
from customers
join customer_invoices
on customer_invoices.customer_id = customers.id
join customer_invoice_details
on customer_invoice_details.customer_invoice_id = customer_invoices.id
where customer_id = 574413;
unexpected result :
customerID last_name first_name invoice_total details_total
574413 terry amine 1900.00 950.00
I need to have the SUM of the total_price of the invoices, and the SUM of the total_price of the details for each customer. In this case I'm supposed to get 950 as total_price for both columns (invoice_total& details_total) but it's not the case. what am I doing wrong & how can I get the correct result please. The answers in similar topics don't have the solution for this case.
When you mix normal columns with aggregate functions (for example SUM), you need to use GROUP BY where you list the normal columns from the SELECT.
The reason for the excessive amount in total_price for invoices is that the SUM is also calculated over each detail row as it is part of the join. Use this:
select c.id as customerID,
c.last_name,
c.first_name,
SUM(ci.total_price) as invoice_total,
SUM((select SUM(d.total_price)
from customer_invoice_details d
where d.customer_invoice_id = ci.id)) as 'detail_total_price'
from customers c
join customer_invoices ci on ci.customer_id = c.id
where c.id = 574413
group by c.id, c.last_name, c.first_name
db-fiddle
I used join against sub queries and then did a sum on the sums
SELECT c.id as customerID,
c.last_name,
c.first_name
SUM(i.sum) as invoice_total,
SUM(d.sum) AS details_total
FROM customers c
JOIN (SELECT id, customer_id, SUM(total_price) AS sum
FROM customer_invoices
GROUP BY id, customer_id) AS i ON i.customer_id = c.id
JOIN (SELECT customer_invoice_id as id, SUM(total_price) AS sum
FROM customer_invoice_details
GROUP BY customer_invoice_id) AS d ON d.id = i.id
WHERE c.id = 574413
GROUP BY c.id, c.name
The issue is in the joining logic. The table customers is used as the driving table in the joins. But in the second join, you are using a derivative key column from the first join, to join with the third tables. This is resulting in a Cartesian output doubling the records from the result from the nth-1 join, which is leading to customer_invoices.total_price getting repeated twice, hence the rolled up value of this field is doubled.
At a high level I feel that the purpose of rolling up the prices is already achieved in SUM(customer_invoice_details.total_price).
But if you have a specific project requirement that SUM(customer_invoices.total_price) should also be obtained and must match with SUM(customer_invoice_details.total_price), then you can do this:
In a separate query, Join customer_invoice_details and customer_invoices. Roll up the pricing fields, and have a result such that you have only one record for one customer ID.
Then use this as a sub-query and join it with the customers table.
You are aggregating along multiple dimensions. This is challenging. I would suggest doing the aggregation along each dimension independently:
select c.id as customerID, c.last_name, c.first_name,
ci.invoice_total,
cid.details_total
from customers c join
(select ci.sum(ci.total_price) as invoice_total
from customer_invoices ci
group by ci.customer_id
) ci
on ci.customer_id = c.id join
(select ci.sum(cid.total_price) as details_total
from customer_invoices ci join
customer_invoice_details cid
on cid.customer_invoice_id = ci.id
group by ci.customer_id
) cid
on cid.customer_id = c.id
where c.id = 574413;
A faster version (for one customer) uses correlated subqueries:
select c.id as customerID, c.last_name, c.first_name,
(select ci.customer_id, sum(ci.total_price) as invoice_total
from customer_invoices ci
where ci.customer_id = c.id
) as invoice_total,
(select ci.customer_id, sum(cid.total_price) as details_total
from customer_invoices ci join
customer_invoice_details cid
on cid.customer_invoice_id = ci.id
where ci.customer_id = c.id
) as details_total
from customers c
where c.id = 574413;
I have a query problem with count. I want to have a column with the number of persons registered to the course.
So far, this is my query:
select
courses.id,
name,
location,
capacity,
(
SELECT count(courses_requests.IDcourse)
FROM courses_requests, courses
WHERE courses_requests.IDcourse = courses.id AND status != "rejected"
) as Registered,
begin_date,
end_date,
price,
active
from courses
But this is giving me problems, it displays the same value for all rows, even if the course doesn't have persons registered in the course
E.G
Capacity Registered
2 1
30 1
It may be simplier to aggregate the outer select, to eliminate the subquery, so something like:
SELECT c.id,
c.name,
c.location,
c.capacity,
COUNT(cr.IDcourse) AS RequestCount
c.begin_date,
c.end_date,
c.price,
c.active
FROM courses c
INNER JOIN courses_requests cr
ON cr.IDcourse = c.id
AND status != "rejected"
GROUP BY c.id,
c.name,
c.location,
c.capacity,
c.begin_date,
c.end_date,
c.price,
c.active
You should connect your subquery to main query:
select courses.id,
courses.name,
courses.location,
courses.capacity,
(SELECT count(courses_requests.IDcourse)
FROM courses_requests,
WHERE courses_requests.ID = courses.id
and status != "rejected" ) as Registered,
begin_date,
end_date,
price,
active
from courses
You can use join to simplify your query ans using SUM() with a condition will give you the count
select
c.id,
c.name,
c.location,
c.capacity,
SUM(cr.status != "rejected") as Registered,
c.begin_date,
c.end_date,
c.price,
c.active
from courses c
JOIN courses_requests cr ON (cr.IDcourse = c.id)
GROUP BY c.id
I am having to set up a query that retrieves the last comment made on a customer, if no one has commented on them for more than 4 weeks. I can make it work using the query below, but for some reason the comment column won't display the latest record. Instead it displays the oldest, however the date shows the newest. It may just be because I'm a noob at SQL, but what exactly am I doing wrong here?
SELECT DISTINCT
customerid, id, customername, user, MAX(date) AS 'maxdate', comment
FROM comments
WHERE customerid IN
(SELECT DISTINCT id FROM customers WHERE pastdue='1' AND hubarea='1')
AND customerid NOT IN
(SELECT DISTINCT customerid FROM comments WHERE DATEDIFF(NOW(), date) <= 27)
GROUP BY customerid
ORDER BY maxdate
The first "WHERE" clause is just ensuring that it shows only customers from a specific area, and that they are "past due enabled". The second makes sure that the customer has not been commented on within the last 27 days. It's grouped by customerid, because that is the number that is associated with each individual customer. When I get the results, everything is right except for the comment column...any ideas?
Join much better to nested query so you use the join instead of nested query
Join increase your speed
this query resolve your problem.
SELECT DISTINCT
customerid,id, customername, user, MAX(date) AS 'maxdate', comment
FROM comments inner join customers on comments.customerid = customers.id
WHERE comments.pastdue='1' AND comments.hubarea='1' AND DATEDIFF(NOW(), comments.date) <= 27
GROUP BY customerid
ORDER BY maxdate
I think this might probably do what you are trying to achieve. If you can execute it and maybe report back if it does or not, i can probably tweak it if needed. Logically, it ' should' work - IF i have understood ur problem correctly :)
SELECT X.customerid, X.maxdate, co.id, c.customername, co.user, co.comment
FROM
(SELECT customerid, MAX(date) AS 'maxdate'
FROM comments cm
INNER JOIN customers cu ON cu.id = cm.customerid
WHERE cu.pastdue='1'
AND cu.hubarea='1'
AND DATEDIFF(NOW(), cm.date) <= 27)
GROUP BY customerid) X
INNER JOIN comments co ON X.customerid = co.customerid and X.maxdate = co.date
INNER JOIN customer c ON X.customerid = c.id
ORDER BY X.maxdate
You need to have subquery for each case.
SELECT a.*
FROM comments a
INNER JOIN
(
SELECT customerID, max(`date`) maxDate
FROM comments
GROUP BY customerID
) b ON a.customerID = b.customerID AND
a.`date` = b.maxDate
INNER JOIN
(
SELECT DISTINCT ID
FROM customers
WHERE pastdue = 1 AND hubarea = 1
) c ON c.ID = a.customerID
LEFT JOIN
(
SELECT DISTINCT customerid
FROM comments
WHERE DATEDIFF(NOW(), date) <= 27
) d ON a.customerID = d.customerID
WHERE d.customerID IS NULL
The first join gets the latest record for each customer.
The second join shows only customers from a specific area, and that they are "past due enabled".
The third join, which uses LEFT JOIN, select all customers that has not been commented on within the last 27 days. In this case,only records without on the list are selected because of the condition d.customerID IS NULL.
But tomake your query shorter, if the customers table has already unique records for customer, then you don't need to have subquery on it.Directly join the table and put the condition on the WHERE clause.
SELECT a.*
FROM comments a
INNER JOIN
(
SELECT customerID, max(`date`) maxDate
FROM comments
GROUP BY customerID
) b ON a.customerID = b.customerID AND
a.`date` = b.maxDate
INNER JOIN customers c
ON c.ID = a.customerID
LEFT JOIN
(
SELECT DISTINCT customerid
FROM comments
WHERE DATEDIFF(NOW(), date) <= 27
) d ON a.customerID = d.customerID
WHERE d.customerID IS NULL AND
c.pastdue = 1 AND
c.hubarea = 1
Two of your table columns are not contained in either an aggregate function or the GROUP BY clause. for example suppose that you have two data rows with the same customer id and same date, but with different comment data. how SQL should aggregate these two rows? :( it will generate an error...
try this
select customerid, id, customername, user,date, comment from(
select customerid, id, customername, user,date, comment,
#rank := IF(#current_customer = id, #rank+ 1, 1),
#current_customer := id
from comments
where customerid IN
(SELECT DISTINCT id FROM customers WHERE pastdue='1' AND hubarea='1')
AND customerid NOT IN
(SELECT DISTINCT customerid FROM comments WHERE DATEDIFF(NOW(), date) <= 27)
order by customerid, maxdate desc
) where rank <= 1