In SQL Server 2016, I have a query as such:
SELECT [Report_date], count(distinct indv_id)
FROM
[dbo].[STG_TABLE] group by report_date order by report_date desc
I get the results as below:
Report_date (No column name)
2020-08-21 47918
2020-08-12 968065
2020-07-31 977804
Now I want to compare the difference between the counts in each row. If the difference is more than 10%, then I need to send an email out in the SSIS package.
How can I go through each row and calculate the difference? I want to look at the first row and compare it with the second row.
You question seems to be about calculating the ratios between rows. For that, use lag(). To get the ratio:
SELECT [Report_date], COUNT(DISTINCT indv_id),
(COUNT(DISTINCT indv_id) * 1.0 / LAG(COUNT(DISTINCT indv_id)) OVER (ORDER BY report_date))
FROM [dbo].[STG_TABLE]
GROUP BY report_date
ORDER BYreport_date DESC;
I'm not sure what results you want, but this is the basic information.
Related
I have a table with user, date and a col each for messages sent and messages received:
I want to get the max of messages_sent/messages_recieved by date and user for that ratio. So this is the output I expect:
Andrew Lean 10/2/2020 10
Andrew Harp 10/1/2020 6
This is my query:
SELECT
ds.date, ds.user_name, max(ds.ratio) from
(select a.user_name, a.date, a.message_sent/ a.message_received as ratio
from messages a
group by a.user_name, a.date) ds
group by ds.date
But the output I get is:
Andrew Lean 10/2/2020 10
Jalinn Kim 10/1/2020 6
In the above output 6 is the correct max ratio for the date grouped but the user is wrong. What am I doing wrong?
With a recent version of most databases, you could do something like this.
This assumes, as in your data, there's one row per user per day. If you have more rows per user per day, you'll need to provide a little more detail about how to combine them or ignore some rows. You could want to SUM them. It's tough to know.
WITH cte AS (
select a.user_name, a.date
, a.message_sent / a.message_received AS ratio
, ROW_NUMBER() OVER (PARTITION BY a.date ORDER BY a.message_sent / a.message_received DESC) as rn
from messages a
)
SELECT t.user_name, t.date, t.ratio
FROM cte AS t
WHERE t.rn = 1
;
Note: There's no attempt to handle ties, where more than one user has the same ratio. We could use RANK (or other methods) for that, if your database supports it.
Here, I am just calculating the ratio for each column in the first CTE.
In the second part, I am getting the maximum results of the ratio calculated in the first part on date level. This means I am assuming each user will have one row for each date.
The max() function on date level will ensure that we always get the highest ratio on date level.
There could be ties, between the ratios for that we can use ROW_NUMBER' OR RANK()` to set a rank for each row based on the criteria that we would like to pass in case of ties and then filter on the rank generated.
with data as (
select
date,
user_id,
messages_sent / messages_recieved as ratio
from [table name]
)
select
date,
max(ratio) as higest_ratio_per_date
from data
group by 1,2
There is a database in place with hourly timeseries data, where every row in the DB represents one hour. Example:
TIMESERIES TABLE
id date_and_time entry_category
1 2017/01/20 12:00 type_1
2 2017/01/20 13:00 type_1
3 2017/01/20 12:00 type_2
4 2017/01/20 12:00 type_3
First I used the GROUP BY statement to find the latest date and time for each type of entry category:
SELECT MAX(date_and_time), entry_category
FROM timeseries_table
GROUP BY entry_category;
However now, I want to find which is the date and time which is the LEAST RECENT among the datetime's I obtained with the query listed above. I will need to use somehow SELECT MIN(date_and_time), but how do I let SQL know I want to treat the output of my previous query as a "new table" to apply a new SELECT query on? The output of my total query should be a single value—in case of the sample displayed above, date_and_time = 2017/01/20 12:00.
I've tried using aliases, but don't seem to be able to do the trick, they only rename existing columns or tables (or I'm misusing them..).There are many questions out there that try to list the MAX or MIN for a particular group (e.g. https://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/ or Select max value of each group) which is what I have already achieved, but I want to do work now on this list of obtained datetime's. My database structure is very simple, but I lack the knowledge to string these queries together.
Thanks, cheers!
You can use your first query as a sub-query, it is similar to what you are describing as using the first query's output as the input for the second query. Here you will get the one row out put of the min date as required.
SELECT MIN(date_and_time)
FROM (SELECT MAX(date_and_time) as date_and_time, entry_category
FROM timeseries_table
GROUP BY entry_category)a;
Is this what you want?
SELECT TOP 1 MAX(date_and_time), entry_category
FROM timeseries_table
GROUP BY entry_category
ORDER BY MAX(date_and_time) ASC;
This returns ties. If you do not want ties, then include an additional sort key:
SELECT TOP 1 MAX(date_and_time), entry_category
FROM timeseries_table
GROUP BY entry_category
ORDER BY MAX(date_and_time) ASC, entry_category;
May I ask why I should use CodeA instead of CodeB for calculating the percentage? The result are totally different.
Thank you so much for your help!
CodeA:
select name, round(sum(amount_paid) /
(select sum(amount_paid) from order_items) * 100.0, 2) as pct
from order_items
group by 1
order by 2 desc;
CodeB:
select name, round((amount_paid /
sum(amount_paid)) * 100.0, 2) as pct
from order_items
group by 1
order by 2 desc;
CodeB is totally wrong because it uses wrong GROUP BY statement (amount_paid column without aggregate function).
Strict databases will trowing error if you try to use this query.
CodeA uses subselect (select sum(amount_paid) from order_items) which calculates total sum(amount_paid) from table and then uses it for calculating percentage for each row.
It is difficult to be sure without knowing the database and the data you are operating on. I believe however that the group by section in SQL is executed before the select section. This means that in CodeB I think the records have already been grouped by the Name column by the time sum(amount_paid) is executed on the amount_paid field. This means it would be calculating the sum of the records by group instead of all the records.
I want to write a query that will have the average(that wont be hard) but when I get that average I want to save it somewhere. Let's I have a average save from last month table_a.last_month_average. And now I run the query again and this would be the current_month_average. I want to compare this two columns and see if the current_month_average increase from last_month_average.
After I compare I would like to output the biggest average number from those two. After I do this I would like to move the current_month_average to last_month_average so that one becomes the old average when next month the query runs.
Is this possible in sql? or maybe there is a better way to do this?any suggestions will help.
After I compare I would like to output the biggest average number from those two. After I do this I would like to move the current_month_average to last_month_average so that one becomes the old average when next month the query runs.
By my understanding, this operation is to select maximum month_average from all history records. So you don't need to keep a record of current_month_average and last_month_average. Instead, a table of all history month average is helpful. Assume there is table named monthaverage with columns (Id, Month, Average), you can query
SELECT TOP 1 T1.*
, CASE WHEN
T1.Average > (SELECT TOP 1 T2.Average
FROM monthaverage T2
WHERE T2.Month < T1.Month
ORDER BY Month DESC)
THEN 'Increased'
ELSE 'Not Increased'
END
FROM monthaverage T1
ORDER BY T1.Average DESC
If you have chance to run it from SQL SERVER 2012, you can leverage LAST_VALUE function. Query is like
SELECT TOP 1 *, CASE WHEN Average > LAST_VALUE(Average) OVER (ORDER BY Month) THEN 'Increased' ELSE 'Not Increased' END
FROM monthaverage
ORDER BY Average DESC
I have tables with:
id desc total
1 baskets 25
2 baskets 15
3 baskets 75
4 noodles 10
I would like to ask the query with output which the sum of total is 40.
The output would be like:
id desc total
1 baskets 25
2 baskets 15
I believe this will get you a list of the results you're looking for, but not with your example dataset because nothing in your example dataset can provide a total sum of 40.
SELECT id, desc, total
FROM mytable
WHERE desc IN (
SELECT desc
FROM mytable
GROUP BY desc
HAVING SUM(total) = 40
)
Select Desc,SUM(Total) as SumTotal
from Table
group by desc
having SUM(Total) > = 40
Not quite sure what you want, but this may get you started
SELECT `desc`, SUM(Total) Total
FROM TableName
GROUP BY `desc`
HAVING SUM(Total) = 40
From reading your question, it sounds like you want a query that returns any subset of of sums that represent a certain target value and have the same description.
There is no simple way to do this. This migrates into algorithmic territory.
Assuming I am correct in what you are after, group bys and aggregate functions will not solve your problem. SQL cannot indicate that a query should be performed on subsets of data until it exhaust all possible permutations and finds the Sums that match your requirements.
You will have to intermix an algorithm into your sql ... i.e a stored procedure.
Or simply get all the data from the database that fits the desc then perform your algorithm on it in code.
I recall there was a CS algorithmic class I took where this was a known Problem:
I believe you could just adapt working versions of this algorithm to solve your problem
http://en.wikipedia.org/wiki/Subset_sum_problem
select desc
from (select desc, sum(total) as ct group by desc)