I have two tables with several columns. All I want is to join both the tables and create two more columns of min and max dates. For example
table data [columns]
ID date instrument
table people
ID birth country
All I want is join these two tables and add two more columns in the "people" table with min and max date groupby ID, as single ID contains a number of dates in data table.
You may try below query -
SELECT P.ID, P.birth, P.country, MIN(D.date) MIN_DATE, MAX(D.date) MAX_DATE
FROM DATA D JOIN PEOPLE P ON D.ID = P.ID
GROUP BY P.ID, P.birth, P.country
SELECT SUB_QUERY.*,MIN(D.DATE) FROM
(SELECT * FROM PEOPLE AS P LEFT JOIN ON DATA AS D) AS SUB_QUERY
GROUP BY P.ID
ORDER BY D.DATE ASC
Related
I have two MySQL-tables:
Persons (pid,name,companyID,companyName)
Orders (oid,companyID,details)
Now I want to count the number of order_id for each companyName as following:
Name Total
-------------------
CompanyName1 : 1200
CompanyName2 : 758
CompanyName3 : 11
I used this query but it's not working properly.
SELECT count(o.oid) as total,p.companyName
FROM orders as o, persons as p
WHERE o.companyID = p.companyID
GROUP BY p.companyName
Use join and group the result by p.companyID
SELECT p.companyName, count(o.oid) as total
FROM orders as o join persons as p
on o.companyID = p.companyID
GROUP BY p.companyID
If you are missing the companies without any orders you can use a left join.
SELECT p.companyName, count(*) as total
FROM persons p
LEFT JOIN orders o ON o.companyID = p.companyID
GROUP BY p.companyID, p.companyName
Please do not use the old, legacy join syntax any more - it is outdated since 1992.
Your data model looks messed up. That you have company ids and names in the person table but no corresponding companies table is highly suspicious.
In any case, presumably there can be multiple rows per company. You can condense the persons table and then join:
SELECT c.companyName, COUNT(*) as total
FROM orders o JOIN
(SELECT DISTINCT companyId, companyName
FROM persons p
) c
ON o.companyID = c.companyID
GROUP BY c.companyName;
However, you should fix the data model so you have a real bona fide companies table -- especially because you seem to care about that entity.
This is a slight variant of the question I asked here
SQL Query for getting maximum value from a column
I have a Person Table and an Activity Table with the following data
-- PERSON-----
------ACTIVITY------------
I have got this data in the database about users spending time on a particular activity.
I intend to get the data when every user has spent the maximum number of hours.
My Query is
Select p.Id as 'PersonId',
p.Name as 'Name',
act.HoursSpent as 'Hours Spent',
act.Date as 'Date'
From Person p
Left JOIN (Select MAX(HoursSpent), Date from Activity
Group By HoursSpent, Date) act
on act.personId = p.Id
but it is giving me all the rows for Person and not with the Maximum Numbers of Hours Spent.
This should be my result.
You have several issues with your query:
The subquery to get hours is aggregated by date, not person.
You don't have a way to bring in other columns from activity.
You can take this approach -- joins and group by, but it requires two joins:
select p.*, a.* -- the columns you want
from Person p left join
activity a
on a.personId = p.id left join
(select personid, max(HoursSpent) as max_hoursspent
from activity a
group by personid
) ma
on ma.personId = a.personId and
ma.max_hoursspent = a.hoursspent;
Note that this can return duplicates for a given person -- if there are ties for the maximum.
This is written more colloquially using row_number():
select p.*, a.* -- the columns you want
from Person p left join
(select a.*,
row_number() over (partition by a.personid order by a.hoursspent desc) as seqnum
from activity a
) a
on a.personId = p.id and a.seqnum = 1
ma.max_hoursspent = a.hoursspent;
I'm trying to get all results of my table with a GROUP BY on 2 columns and get the last insertions.
"Prices" table :
My Request :
SELECT DISTINCT p.*
FROM prices p
JOIN (
SELECT MAX(created_at) as "last_created"
FROM prices
WHERE station_id = 27210003
GROUP BY station_id, fuel_id) as sub
ON sub.last_created = p.created_at
WHERE p.station_id = 27210003
GROUP BY p.station_id, p.fuel_id
Results are 3 lines but wrong line because not last created in my DB -_-'
Please help me !!! >_<'
Thx
Since you're selecting a specific station_id in the WHERE clause, you don't need to include that in GROUP BY.
The subquery has to return the columns you're grouping on, and then you have to include them in the ON clause.
And you don't need GROUP BY in the outer query, since the JOIN should ensure that there's just one row for each fuel_id (unless there are duplicate created_at for the same fuel_id and station_id).
SELECT DISTINCT p.*
FROM prices p
JOIN (
SELECT fuel_id, MAX(created_at) as "last_created"
FROM prices
WHERE station_id = 27210003
GROUP BY fuel_id) as sub
ON sub.last_created = p.created_at AND sub.fuel_id = p.fuel_id
WHERE p.station_id = 27210003
I'd like to sum two columns from two different tables and then group it by user ID (uid). I did fiddle but seems to multipling the results by the number of rows in a column.
http://sqlfiddle.com/#!9/433a5e/3
You have multiple rows for each uid in both table. Hence, for a uid, you get a Cartesian product -- 2 rows in one table for a uid and 3 rows in the other become 6 rows with lots of duplicated data.
SO, aggregate the data before doing the join:
select s.uid, sumscore, sumorder
from (select s.uid, sum(s.score) as sumscore
from scores s
group by s.uid
) s left join
(select o.uid, sum(o.order) sumorder
from orders o
group by o.uid
) o
on o.uid = s.uid;
Here are the results in a SQL Fiddle.
You may be looking for this. Try this and let me know is it helpful or not for you.
SELECT s.uid, SUM(s.score) as score_tot, (SELECT SUM(orders.order) FROM orders WHERE orders.uid = s.uid GROUP BY orders.uid) as order_tot FROM scores as s GROUP BY s.uid
sqlfiddle here
I have two tables customers and orders, below is the structure.
Table - customers
id
customer_name
Table - orders
id
order_id
customer_id
customers table have customers records and orders table have orders placed by customers,
customer_id in orders table is linked to the id field of customers table.
Now one customer can have zero or one or more than one orders, i want to get the last order placed by customers only.
when i run the following query a simple invisible join, it returns all the orders by the customer
SELECT customers.customer_name,orders.order_id FROM orders,customers WHERE orders.customer_id=customers.id
I have also tried different JOIN statements but cannot get the last order by the customer, i want to get it in one SQL query for all customers.
Thank you in advance for your help.
In MySQL there is just few ways to make it work (that I now actually). The first one is sort your table as desc before the join:
SELECT c.customer_name, o.customer_id, o.order_id,o.id FROM customers c
INNER JOIN orders o
ON o.id = (SELECT id FROM orders WHERE customer_id = c.id ORDER BY id DESC LIMIT 1)
Using in real time is the only way to get it done, but if you need to make some join on not real time you can create a temporary table or a alias table sorting it to make your select, like this:
CREATE TABLE tmp_your_table AS
SELECT * FROM orders ORDER BY id DESC
So now you are able to make this join work:
SELECT c.customer_name, o.customer_id, o.order_id,o.id FROM customers c
INNER JOIN tmp_your_table o ON o.id = tmp_your_table.id
Try this query
SELECT
c.customer_name,
max(o.order_id)
FROM
customers c
INNER JOIN
orders o
ON
o.customer_id = c.id
GROUP BY
c.customer_name
You don't have any date field in the order table so assuming the latest order will be the one which has max(order_id).
Try this query
SELECT
c.customer_name,
o.order_id
FROM
customers c
INNER JOIN
orders o
ON
o.customer_id = c.id
ORDER BY
o.id desc
LIMIT 1;