I have a query with WHERE EXISTS and DISTINCT. I just want to find distinct emails with same order_id
How can I make this faster
select DISTINCT(user_email)
from (
SELECT *
FROM orders mto
WHERE EXISTS
(
SELECT 1
FROM orders mti
WHERE mti.order_id = mto.order_id
LIMIT 1, 1
)
) as z
INNER JOIN marketplaces as u ON z.ump_id = u.id
You are doing excess/needless work - the EXISTS will always return TRUE in your situation.
If you want a list of all (unique) emails which have at least 1 order, then
SELECT
user_email
FROM
marketplaces
LEFT JOIN
orders ON ump_id = marketplaces.id
WHERE orders.id IS NOT NULL
GROUP BY user_email
If you want to get a list with all (unique) emails for a given order ID, then
SELECT
user_email
FROM
orders
LEFT JOIN
orders ON ump_id = marketplaces.id
WHERE orders.id = 17
GROUP BY user_email
Related
I have a MySQL query which I want to execute to see who is the employee with the best skill X in a company I work for. To do this I randomly pick a company from my cv_profile (skill_cv_test) and find all users who work there for the same employer. And then I randomly choose a skill I have.
The result should either be zero or a list.
But when testing with PHPMyAdmin I get results where I don't see any row, but the status says there is at least one row.
Here's an example of the message I get: https://imgur.com/bVMH716
I have been trying different structures, even "walling" the query with another query, different joins.
SELECT
DISTINCT(sv.usr_id),
u.first_name AS fn,
u.last_name AS ln,
c.name AS company,
s.name AS skill
FROM
(
SELECT
MAX(last_change) as date,
id,
usr_id,
skill_id
FROM skill_valuations
GROUP BY usr_id, skill_id
ORDER BY date
) sv
LEFT JOIN skill_valuations skv ON skv.last_change = sv.date
INNER JOIN
(
SELECT
DISTINCT(skct.comp_id),
skct.usr_id AS usr_id,
skct.category
FROM skill_cv_test skct
WHERE skct.end_date IS NULL AND skct.comp_id IN (SELECT comp_id FROM (SELECT comp_id FROM skill_cv_test WHERE usr_id = 1 ORDER BY RAND() LIMIT 1) x)
) uqv ON uqv.usr_id = sv.usr_id
INNER JOIN
(
SELECT skill_id
FROM usr_skills
WHERE usr_id = $uid
ORDER BY RAND()
LIMIT 1
) usq ON usq.skill_id = sv.skill_id
LEFT JOIN companies c ON c.id = uqv.comp_id
LEFT JOIN skills s ON s.id = sv.skill_id
LEFT JOIN users u ON u.id = sv.usr_id
As mentioned before, I expect either no results or a result of at least one row.
One table is Users with id and email columns.
Another table is Payments with id, created_at, user_id and foo columns.
User has many Payments.
I need a query that returns each user's email, his last payment date and this last payment's foo value. How do I do that? What I have now is:
SELECT users.email, MAX(payments.created_at), payments.foo
FROM users
JOIN payments ON payments.user_id = users.id
GROUP BY users.id
This is wrong, because foo value does not necessarily belong to user's most recent payment.
Try this :
select users.email,foo,create_at
from users
left join(
select a.* from payments a
inner join (
select id,user_id,max(create_at)
from payments
group by id,user_id
)b on a.id = b.id
) payments on users.id = payments.user_id
If users has no payment yet, then foo and create_at would return NULL. if you want to exclude users who has no payment, then use INNER JOIN.
One approach would be to use a MySQL version of rank over partition and then select only those rows with rank = 1:
select tt.email,tt.created_at,tt.foo from (
select t.*,
case when #cur_id = t.id then #r:=#r+1 else #r:=1 end as rank,
#cur_id := t.id
from (
SELECT users.id,users.email, payments.created_at, payments.foo
FROM users
JOIN payments ON payments.user_id = users.id
order by users.id asc,payments.created_at desc
) t
JOIN (select #cur_id:=-1,#r:=0) r
) tt
where tt.rank =1;
This would save hitting the payments table twice. Could be slower though. Depends on your data!
I have an sql query that returns a list of residential units, and a subquery that is supposed to get the last entered bill for that unit.
However when I add LIMIT 1 to the subquery, no bill entries are returned? If I leave it out, I get duplicate unit rows depending on the number of bill for the unit.
select * from unit u
left join (select id as billId, unit_id, added_on, end_reading, bill_type from bills
order by id desc) b ON unit_id = u.id
where community_Id = 1
and unit_section = 7
and unit_floor in (1,2,3,4,5)
order by unit_floor, display_order asc;
Anyone know how I can the subquery result limited to 1 bill?
When using joins that duplicate your results, add a group by statement. It's an alternative of the distinct from a simple select
select * from unit u
left join (select id as billId, unit_id, added_on, end_reading, bill_type from bills
order by id desc) b ON unit_id = u.id
where community_Id = 1
and unit_section = 7
and unit_floor in (1,2,3,4,5)
group by u.id
order by unit_floor, display_order asc;
Think you will need a sub query to get the first (lowest) id for each unit_id from the bills table. Then use that to join between the unit and bills table, getting the other matching columns from bills for that lowest id
SELECT u.*, bills.*
FROM unit u
LEFT OUTER JOIN
(
SELECT unit_id, MIN(id) AS min_id
FROM bills
GROUP BY unit_id
) b ON b.unit_id = u.id
LEFT OUTER JOIN bills
ON b.unit_id = bills.unit_id
AND b.min_id = bills.id
WHERE u.community_Id = 1
AND u.unit_section = 7
AND u.unit_floor in (1,2,3,4,5)
ORDER BY u.unit_floor, u.display_order asc;
I have troubles getting proper data.
I have table structure like:
id INT(11) AI
order_id INT(11)
status varchar(45)
This table log status changes for orders.
So order_id's will have few statuses.
Now I need to select rows and group them by order_id, where order never had status (not even one status with given order_id) != 'example'
We don't show orders, where one of members had status = example
Sample data
1 12 ready
1 12 example
2 13 ready
2 13 sent
So I don't want order 12 to show at all, because one of it members have "example" status
I've tried grouping results, but it's not enough.
you can do it by simple join query :
select a.order_id
from ordrstatus as a left outer join (select orderid , count(*) as status from orderstatus where status = 'example' group by orderid) as b on a.orderid = b.orderid
where b.status = 0 or b.status is NUll
Join query always run faster then IN query . by using Join in query it will run only one time .
You can try like this...it will return all order id which never had status -example
Select
Order_id,
from TableName A where Not Exists(
Select id from TableName B where
status='example' and
a.Order_id=b.Order_id
)
group by Order_id
Not quite sure if you want the records for order which have had a status of example, or ones which have never had a status of example
To get a list of orders (with the status grouped up) which have had a status of example:-
SELECT a.order_id, GROUP_CONCAT(a.status)
FROM SomeTable a
INNER JOIN
(
SELECT order_id, COUNT(*)
FROM SomeTable
WHERE status = 'example'
GROUP BY order_id
) b
ON a.order_id = b.order_id
GROUP BY order_id
To get those which have NEVER had a status of exmaple
SELECT a.order_id, GROUP_CONCAT(a.status)
FROM SomeTable a
LEFT OUTER JOIN
(
SELECT order_id, COUNT(*)
FROM SomeTable
WHERE status = 'example'
GROUP BY order_id
) b
ON a.order_id = b.order_id
WHERE b.order_id IS NULL
GROUP BY order_id
EDIT
SELECT a.order_id, GROUP_CONCAT(a.status)
FROM SomeTable a -- Statuses
LEFT OUTER JOIN
(
SELECT order_id, COUNT(*)
FROM SomeTable
WHERE status = 'example'
GROUP BY order_id
) b -- Get any order id which has had a status of example (as a LEFT JOIN)
ON a.order_id = b.order_id
INNER JOIN
(
SELECT order_id, MAX(id) AS Latestid
FROM SomeTable
GROUP BY order_id
) c -- Get the latest status for each order (ie, max id)
ON a.order_id = c.order_id
LEFT OUTER JOIN
(
SELECT order_id, id
FROM SomeTable
WHERE status = 'example2'
) d -- Get the id of the order status of example2
ON a.order_id = d.order_id AND c.Latestid = d.id -- join on the same order id and that the record id matches the latest record id
WHERE b.order_id IS NULL -- reject those where a match was found on example for any status
AND d.order_id IS NULL -- reject those where a match was found on example2 for the latest status
GROUP BY order_id
try this
SELECT Order_ID FROM tbl_Orders
WHERE Status NOT IN ('example')
GROUP BY Order_ID
SELECT DISTINCT x.order_id
FROM order_status x
LEFT
JOIN order_status y
ON y.order_id = x.order_id
AND y.status = 'example'
WHERE y.id IS NULL;
I have two tables:
users:
user_id user_name
data:
user_id user_data user_time
I wan to select the latest entry from the data table, but return the user_name, user_id, user_data and user_time.
I have tried the following query, but it returns the first entry, not the last for each user:
sql = "SELECT users.user_name, users.user_id, data.user_data, data.user_time
FROM users
INNER JOIN data ON data.user_id = users.user_id
GROUP BY users.user_name
ORDER BY data.user_time DESC";
Use GROUP BY and MAX, WHERE...IN:
SELECT u.user_id, u.user_name, d.user_data, d.user_time
FROM users u
INNER JOIN data d ON d.user_id = u.user_id
WHERE (d.user_id, d.user_time) =
(SELECT user_id, MAX(user_time) FROM data GROUP BY user_id)
I think you had better add data_id column to data table.
Unless data_id, both user_id and user_time are necessary for PRIMARY KEY(and user_time is not always unique, not reliable)
If there is data_id, it can be bitly simple:
SELECT u.user_id, u.user_name, d.user_data, d.user_time
FROM users u
INNER JOIN data d ON d.data_id =
(SELECT data_id FROM data
WHERE user_id = u.user_id ORDER BY data_time DESC LIMIT 1)