This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
SQL Query to get latest price
I have a database containing stock price history. I want to select most recent prices for every stock that is listed. I know PostreSQL has a DISTINCT ON statement that would suit ideally here.
Table columns are name, closingPrice and date; name and date together form a unique index.
The easiest (and very uneffective) way is
SELECT * FROM stockPrices s
WHERE s.date =
(SELECT MAX(date) FROM stockPrices si WHERE si.name = s.name);
Much better approach I found is
SELECT *
FROM stockPrices s JOIN (
SELECT name, MAX(date) AS date
FROM stockPrices si
GROUP BY name
) lastEntry ON s.name = lastEntry.name AND s.date = lastEntry.date;
What would be an efficient way to do this? What indexes should I create?
duplicate of:
SQL Query to get latest price
I think that your second approach is very efficient. What's its problem?
You have to add indexes to name and date.
Related
I am working in a task and got stuck at particular question. I am new to SQL so I am reaching out to this platform for the support. Below are the 2 tables. 1st is Theatre_play_table and 2nd is Ticketsales table.
Question: List titles, directors and writers of all shows/plays with the highest total sale.
Theatre_play_table
Ticketsales table
I have pasted screenshot of some part of the table. ID column in both the table represents the same information. Last column in Ticketsales table is Totalamount.
I have tried with below query;
Select theatre_play.title, theatre_play.director, theatre_play.writer, sum(totalamount)
from theatre_play, totalsales
where theatre_play.id = totalsales.id
group by theatre_play.title, theatre_play.director, Theatre_play.writer
order by sum(totalamount) desc
fetch first 3 rows only;
The above approach is not useful when data is huge. I wanted to apply max(sum(totalamount)) but oracle threw an error.
Can anyone please help me solve this question?
If I understand you right, the issue is to get the three highest values?
Then try something like this:
select * from (
Select dpro.title, dpro.director, dpro.writer, sum(fth.totalamount)
from dpro
join fth on dpro.id = fth.id
group by dpro.title, dpro.director, dpro.writer
order by sum(totalamount) desc )
where rownum <=3
This is on a Postgres server using SQL. I have a supply_chain table in which I need to pull the warehouse_id from, and an order table in which I need to pull the total returns. Located on the same server.
I need to combine them on the delivery zipcode from the order table and the zipcode on the supply_chain table. I am unsure the best way to join this in SQL.
SELECT deliveryzipcode, COUNT(OrderReturned) AS Total_returned
FROM transactions_log
WHERE OrderReturned= 'Yes'
GROUP BY deliveryzipcode;
This query will successfully return the number of returns based on zipcode. So basically I need to pull those warehouse_id's and count them.
Apologize in advance for not wording this question well.
You can try this :
SELECT sc.warehouse_id, sc.zipcode, tl.Total_returned
FROM logistics_supply_chain_network AS sc
INNER JOIN
(
SELECT deliveryzipcode, COUNT(OrderReturned) AS Total_returned
FROM transactions_log
WHERE OrderReturned= 'Yes'
GROUP BY deliveryzipcode
) AS tl
ON tl.deliveryzipcode = sc.zipcode ;
This question already has answers here:
Calculate a Running Total in SQL Server
(15 answers)
Closed 4 years ago.
I need to create a different column of total sales which is the total of the sales units till that row. As our sales unit will increase, the total sales will increase row by row. I have attached the image to get the clear idea.
Screenshot
One method is use to use of subquery with correlation approach
select *,
(select sum(sales) from table where product = t.product and ? <= t.?) TotalSales
from table t
However, you would required ? (i.e. rowid or id) column that could specify your column ordering.
You can use the following query, which adds up all the sales upto that rowId and for the specific product.
select (select sum(ids)
from TBL_NAME T1
where T1.rowid <= TBL_NAME.rowid and PRODUCT=TBL_NAME.PRODUCT
) as TotalSales
from TBL_NAME;
Following answer is for Oracle DB, you can understand the query and easily convert it to the product you want.
This question already has answers here:
How can I remove duplicate rows?
(43 answers)
Closed 8 years ago.
suppose you have a data set having 3 columns: ID, user, date.
is it possible to filter the data based on the minimum date even if some of the rows have identical IDs?
sorry if the question is a bit unclear. hopefully the image below will help clear things.
there are two records having ID=1, with different users as well as dates. what i want to retrieve is the record having an ID=1, USER=A, DATE=2013-01-20 because its date is earlier than that of the second record (ID=1, USER=A, DATE=2013-01-21)
i want to achieve the same effect for the three records having an ID=2. the desired record is ID=2,USER=C,DATE=2013-10-20
basically i want to group these records by their IDs and then from that grouping, get the one with the lowest date
SELECT id, user, date
FROM OriginalData od
WHERE date = (SELECT MIN(date)
FROM OriginalDate od1
WHERE od.id = od1.id)
Select * from table_name where date in
( select MIN(date) from table_name)
You have tyo use Group By clause on Id attribute.
Use the following syntax
select * from tab1 where (id, date) in (select id, min(date) from tab1 group by(id))
I have a MS SQL 2008 table of survey responses and I need to produce some reports. The table is fairly basic, it has a autonumber key, a user ID for the person responding, a date, and then a bunch of fields for each individual question. Most of the questions are multiple choice and the data value in the response field is a short varchar text representation of that choice.
What I need to do is count the number of distinct responses for each choice option (ie. for question 1, 10 people answered A, 20 answered B, and so forth). That is not overly complex. However, the twist is that some people have taken the survey multiple times (so they would have the same User ID field). For these responses, I am only supposed to include the latest data in my report (based on the survey date field). What would be the best way to exclude the older survey records for those users that have multiple records?
Since you didn't give us your DB schema I've had to make some assumptions but you should be able to use row_number to identify the latest survey taken by a user.
with cte as
(
SELECT
Row_number() over (partition by userID, surveyID order by id desc) rn,
surveyID
FROM
User_survey
)
SELECT
a.answer_type,
Count(a.anwer) answercount
FROM
cte
INNER JOIN Answers a
ON cte.surveyID = a.surveyID
WHERE
cte.rn = 1
GROUP BY
a.answer_type
Maybe not the most efficient query, but what about:
select userid, max(survey_date) from my_table group by userid
then you can inner join on the same table to get additional data.