I have a relational database in SQL Server which I use to store Products, Competitor Companies and Competitor Prices. I regularly add new records to the Competitor Prices table rather than updating existing records so I can track prices changes over time.
I want to build a query which given a particular product, find the most recent price from each of the competitors. It is possible that each competitor doesn't have a price recorded.
Data Example
tblCompetitorPrices
+-----+----------+-------------+-----+----------+
|cp_id|product_id|competitor_id|price|date_added|
+-----+----------+-------------+-----+----------+
|1 |1 |3 |70.00|15-01-2014|
+-----+----------+-------------+-----+----------+
|2 |1 |4 |65.10|15-01-2014|
+-----+----------+-------------+-----+----------+
|3 |2 |3 |15.20|15-01-2014|
+-----+----------+-------------+-----+----------+
|4 |1 |3 |62.30|19-01-2014|
+-----+----------+-------------+-----+----------+
And I want the query to return...
+-----+----------+-------------+-----+----------+
|cp_id|product_id|competitor_id|price|date_added|
+-----+----------+-------------+-----+----------+
|4 |1 |3 |62.30|19-01-2014|
+-----+----------+-------------+-----+----------+
|2 |1 |4 |65.10|15-01-2014|
+-----+----------+-------------+-----+----------+
I can currently access all the prices for the product, but I'm not able to filter the results so only the most recent price for each competitor is shown - I'm really unsure...here is what I have so far....
SELECT cp_id, product_id, competitor_id, price, date_added
FROM tblCompetitorPrices
WHERE product_id = '1'
ORDER BY date_added DESC
Thanks for any help!
Try this,
SELECT cp_id, product_id, competitor_id, price, date_added
FROM tblCompetitorPrices
WHERE product_id = '1' AND date_added=( SELECT MAX(date_added)
FROM tblCompetitorPrices
WHERE product_id = '1')
ORDER BY date_added DESC
As an alternative, you can also use ROW_NUMBER() which is a Window function that generates sequential number.
SELECT cp_id,
product_id,
competitor_id,
price,
date_added
FROM (
SELECT cp_id,
product_id,
competitor_id,
price,
date_added,
ROW_NUMBER() OVER (PARTITION BY competitor_id
ORDER BY date_added DESC) rn
FROM tblCompetitorPrices
WHERE product_ID = 1
) a
WHERE a.rn = 1
This query can easily be modified to return latest record for each competitor in every product.
It took a while since I had to test the query myself, so yeah, here it is. Try it, it may help you even a bit with clause combinations. :) It's shorter.
SELECT cp_id, product_id, competitor_id, price, MAX(date_added) as last_date
FROM tblCompetitorPrices
WHERE product_id = '1'
GROUP BY competitor_id
Related
The table looks like that:
|ID |status |Date |
|1 |declined|01.01.2010|
|1 |declined|04.01.2010|
|1 |approved|06.01.2010|
|2 |approved|05.02.2010|
|3 |NULL |05.02.2010|
So I wanna group them by ID but at the same time I want to get the latest status for each group
I tried using "Having" but it didn't work for me (I don't know how to use group on everything except status, and to choose only the latest value of status) for each group
Expected result:
|ID |status |Date |
|1 |approved|06.01.2010|
|2 |approved|05.02.2010|
|3 |NULL |05.02.2010|
You can use a correlated subquery:
select t.*
from yourtable t
where t.date = (select max(t2.date) from yourtable t2 where t2.id = t.id);
IS ID a group within the context of your question?
The query down here shows the id's that have approved or null as status.
Id's (or groups) are displayed in ascending order.
SELECT * FROM `t1`
WHERE status ='approved' OR status ='NULL'
ORDER BY date ASC
example: https://dbfiddle.uk/?rdbms=mysql_5.7&fiddle=b61dc18af6193dc30cd9692679e6513e
I have a table structured like this where I need to get the ID's last number, how many people's ID ends with that number, and the person with the highest ID:
Members: |ID |Name |
-----------------
|123 |foo |
|456 |bar |
|789 |boo |
|1226|far |
The result I need to get looks something like this
|LAST_NUMBER |OCCURENCES |HIGHEST_ID_GUY |
---------------------------------------------
|3 |1 |foo |
|6 |2 |far |
|9 |1 |boo |
However, while I can get the first two results to display correctly, I have no idea how to display HIGHEST_ID_GUY. My code looks like this:
SELECT DISTINCT SUBSTR(id, LENGTH(id - 1), LENGTH(id)) AS LAST_NUMBER,
COUNT(*) AS OCCURENCES
/* This is where I need to add HIGHEST_ID_GUY */
FROM Members
GROUP BY SUBSTR(id, LENGTH(id - 1), LENGTH(id))
ORDER BY LAST_NUMBER
Any help appreciated :)
If id is a number, then use arithmetic operations:
select mod(id, 10) as last_digit,
count(*),
max(name) keep (dense_rank first order by id desc) as name_at_biggest
from t
group by mod(id, 10);
If id is a string, then you need to convert to a number or something similar to define the "highest id". For instance:
select substr(id, -1) as last_digit,
count(*),
max(name) keep (dense_rank first order by to_number(id) desc) as name_at_biggest
from t
group by substr(id, -1);
Please feel free to change or suggest me to change my title to better sound on what I am trying to ask.
I have a query that gives the following result:
select
Customer.customer_id,
Transaction.amount
From Customer inner join Transaction on Customer.customer_id = Transcation.coustomer_id
Result:
customer_id| amount
01456 |50
01456 |100
01456 |400
01456 |0
01963 |50
01963 |100
01963 |221
01963 |0
Now, I want to add a priority field to give me a priority of 1, 2, or 3. The lower the amount, the higher the priority. Note: I want to replace 0 with text 'Negative'. Ranking amount expect 0.
This is what I want.
customer_id| amount| priority
01456| 50| 3
01456| 100| 2
01456| 400| 1
01456| 0| Negative
01963| 50| 3
01963| 100| 2
01963| 221| 1
01963| 0| Negative
Is this achievable? Your help will be greatly appreciated.
Window functions like ROW_NUMBER() are perfect for this:
SELECT c.customer_id,
t.amount,
ROW_NUMBER() over (PARTITION BY customer_id ORDER BY amount desc) priority
FROM Customer c
JOIN [Transaction] t on c.customer_id = t.customer_id
The partition by resets the numbering on each unique customer_id, and the order by decides which direction and order to number the rows.
Use row_number() or rank():
select customer_id, amount,
row_number() over (partition by customer_id order by amount desc) as priority
from t;
I've a table temp(name int,count int). It stores:-
a|count
1|10
1|8
1|4
1|2
2|10
2|6
2|1
I want it's rows to be numbered, corresponding to a given name(also, note that count has to be in decreasing order), i.e, :-
a|count|row
1|10 |1
1|8 |2
1|4 |3
1|2 |4
2|10 |1
2|6 |2
2|1 |3
I tried How to show row numbers in PostgreSQL query? this post, but it just seems to number it from 1 to 7 and not name-wise. Can someone please help me with this? Thanks!
Use row_number() function
select a, count, row_number() over(partition by a order by count desc) as rn
from tablename
If I have a jobs table like:
|id|created_at |status |
----------------------------
|1 |01-01-2015 |error |
|2 |01-01-2015 |complete |
|3 |01-01-2015 |error |
|4 |01-02-2015 |complete |
|5 |01-02-2015 |complete |
|6 |01-03-2015 |error |
|7 |01-03-2015 |on hold |
|8 |01-03-2015 |complete |
I want a query that will group them by date and count the occurrence of each status and the total status for that date.
SELECT created_at status, count(status), created_at
FROM jobs
GROUP BY created_at, status;
Which gives me
|created_at |status |count|
-------------------------------
|01-01-2015 |error |2
|01-01-2015 |complete |1
|01-02-2015 |complete |2
|01-03-2015 |error |1
|01-03-2015 |on hold |1
|01-03-2015 |complete |1
I would like to now condense this down to a single row per created_at unique date with some sort of multi column layout for each status. One constraint is that status is any one of 5 possible words but each date might not have one of every status. Also I would like a total of all statuses for each day. So desired results would look like:
|date |total |errors|completed|on_hold|
----------------------------------------------
|01-01-2015 |3 |2 |1 |null
|01-02-2015 |2 |null |2 |null
|01-03-2015 |3 |1 |1 |1
the columns could be built dynamically from something like
SELECT DISTINCT status FROM jobs;
with a null result for any day that doesn't contain any of that type of status. I am no SQL expert but am trying to do this in a DB view so that I don't have to bog down doing multiple queries in Rails.
I am using Postresql but would like to try to keep it straight SQL. I have tried to understand aggregate function enough to use some other tools but not succeeding.
The following should work in any RDBMS:
SELECT created_at, count(status) AS total,
sum(case when status = 'error' then 1 end) as errors,
sum(case when status = 'complete' then 1 end) as completed,
sum(case when status = 'on hold' then 1 end) as on_hold
FROM jobs
GROUP BY created_at;
The query uses conditional aggregation so as to pivot grouped data. It assumes that status values are known before-hand. If you have additional cases of status values, just add the corresponding sum(case ... expression.
Demo here
An actual crosstab query would look like this:
SELECT * FROM crosstab(
$$SELECT created_at, status, count(*) AS ct
FROM jobs
GROUP BY 1, 2
ORDER BY 1, 2$$
,$$SELECT unnest('{error,complete,"on hold"}'::text[])$$)
AS ct (date date, errors int, completed int, on_hold int);
Should perform very well.
Basics:
PostgreSQL Crosstab Query
The above does not yet include the total per date.
Postgres 9.5 introduces the ROLLUP clause, which is perfect for the case:
SELECT * FROM crosstab(
$$SELECT created_at, COALESCE(status, 'total'), ct
FROM (
SELECT created_at, status, count(*) AS ct
FROM jobs
GROUP BY created_at, ROLLUP(status)
) sub
ORDER BY 1, 2$$
,$$SELECT unnest('{total,error,complete,"on hold"}'::text[])$$)
AS ct (date date, total int, errors int, completed int, on_hold int);
Up to Postgres 9.4, use this query instead:
WITH cte AS (
SELECT created_at, status, count(*) AS ct
FROM jobs
GROUP BY 1, 2
)
TABLE cte
UNION ALL
SELECT created_at, 'total', sum(ct)
FROM cte
GROUP BY 1
ORDER BY 1
Related:
Grouping() equivalent in PostgreSQL?
If you want to stick to a simple query, this is a bit shorter:
SELECT created_at
, count(*) AS total
, count(status = 'error' OR NULL) AS errors
, count(status = 'complete' OR NULL) AS completed
, count(status = 'on hold' OR NULL) AS on_hold
FROM jobs
GROUP BY 1;
count(status) for the total per date is error-prone, because it would not count rows with NULL values in status. Use count(*) instead, which is also shorter and a bit faster.
Here is a list of techniques:
For absolute performance, is SUM faster or COUNT?
In Postgres 9.4+ use the new aggregate FILTER clause, like #a_horse mentioned:
SELECT created_at
, count(*) AS total
, count(*) FILTER (WHERE status = 'error') AS errors
, count(*) FILTER (WHERE status = 'complete') AS completed
, count(*) FILTER (WHERE status = 'on hold') AS on_hold
FROM jobs
GROUP BY 1;
Details:
How can I simplify this game statistics query?