Hi I have a table with following columns:
ID
student_id
score (int)
scanned_date
close_date.
A script is run every week. it collects a score for each student every week. Each week the scores remain the same. When the script is run for the first time, it enters ID, Student_id, score, scanned_date and Null for Close_date for each student.
For each additional scan, if the score is same as last week's score then, the script does nothing.
But if a new score is found, then it enter's the date in the close_date field and enters a new row containing id, student_id, score, scanned_date and Null for close date.
I'm trying to build a sql statement which will help me build a timeline graph. For each distinct scanned_date, it will return sum of all the scores for each student so that I can build a graph.
is that possible to do?
-Maria
The following query extracts all the distinct scanned dates and them joins them back to the table to find what records are active on each date. It then aggregates the results by date:
select dates.scanned_date,
count(t.id) as numids,
sum(score) as sumscore
from (select distinct scanned_date from t) as dates left outer join
t
on dates.scanned_date >= t.scanned_date and
dates.scanned_date < t.close_date
group by dates.scanned_date
order by 1
Related
I have a sales data table with cust_ids and their transaction dates.
I want to create a table that stores, for every customer, their cust_id, their last purchased date (on the basis of transaction dates) and the count of times they have purchased.
I wrote this code:
SELECT
cust_xref_id, txn_ts,
DENSE_RANK() OVER (PARTITION BY cust_xref_id ORDER BY CAST(txn_ts as timestamp) DESC) AS rank,
COUNT(txn_ts)
FROM
sales_data_table
But I understand that the above code would give an output like this (attached example picture)
How do I modify the code to get an output like :
I am a beginner in SQL queries and would really appreciate any help! :)
This would be an aggregation query which changes the table key from (customer_id, date) to (customer_id)
SELECT
cust_xref_id,
MAX(txn_ts) as last_purchase_date,
COUNT(txn_ts) as count_purchase_dates
FROM
sales_data_table
GROUP BY
cust_xref_id
You are looking for last purchase date and count of distinct transaction dates ( like if a person buys twice, it should be considered as one single time).
Although you mentioned you want count of dates but sample data shows you want count of distinct dates - customer 284214 transacted 9 times but distinct will give you 7.
So, here is the SQL you can use to get your result.
SELECT
cust_xref_id,
MAX(txn_ts) as last_purchase_date,
COUNT(distinct txn_ts) as count_purchase_dates -- Pls note distinct will count distinct dates
FROM sales_data_table
GROUP BY 1
Scenario: Person A takes test B three times in the span of two year. There will be three entries for that person. However, I need to write a query that tells me the number of Persons that have taken a test(just one, the latest test). The problem with this is I have a column labeled, Test_Month (xx) and Test_year(xx).
What I need: I need to be able to just pull the test with the most recent test month and year, basically the most recent test they took. (For example(see pic below) I need, the record for 2/20 only.)
I have no idea how to retrieve only one record per person by the last test they took based on the separate columns test_Month and test_year.
You can use window functions:
select *
from (
select
t.*,
row_number() over(
partition last_name, firt_name
order by test_year desc, test_month desc
) rn
from mytable t
) t
where rn = 1
I have a table that contains multiple registration periods (date and time for the start of the registration, as well as date and time for when that instance of registration ends). For each row (registration period), there is a status column that contains the status at the end of the registration period. I was trying to get the status associated with the most recent end date of registration per a given ID. I've used a window function to get the most recent end date of interest per ID, and then I wanted to LEFT JOIN on ID and end date to get the status from the same table on which I used the window function. There should really just be one just one combination for a given end date and status per ID, but somehow I get more rows that what's in the left table.
Like I mentioned earlier, my approach was to use a window function to get MAX(end_date) per ID and some other column, let's call it enrollment_number. Then use LEFT JOIN on this table and its parent table to bring in status associated with that date only. Later, I'd like to use the result of this join to bring in the status associated with the end date into other tables where I need it.
WITH
my_first_test AS
(
SELECT my_id,
enrollment_number,
MAX(end_date_of_enrollment) OVER (partition by my_id, enrollment_number) AS end_date_enrolled
FROM enrollments
)
SELECT mft.my_id, mft.end_date_enrolled, e.status
FROM my_first_test AS mft
LEFT JOIN enrollments AS e
ON mft.my_id = e.my_id AND mft.end_date_enrolled = e.end_date_enrolled;
The CTE returns 42917 rows, same number of rows as in the enrollments table, which it should be if I understand it correctly.
Then, I LEFT JOIN enrollments, to bring in information from the status column also contained in the enrollments table. The LEFT JOIN is done on my_id and end_date_enrolled.
I expect 42917 rows in the resulting table, because my_id and end_date_enrolled together should be unique. However, I get slightly more rows in my final table - 44408. I was wondering if the StackOverflow community would be able to help me solve this mystery. I am using SQL in AWS Redshift.
You have duplicates in enrollments. You can find them with aggregation:
SELECT my_id, end_date_enrolled, COUNT(*)
FROM enrollments AS e
GROUP BY my_id, end_date_enrolled
HAVING COUNT(*) > 1;
Medical records in my Crystal Report are sorted in this order:
...
Group 1: Score [Level of Risk]
Group 2: Patient Name
...
Because patients are sorted by Score before Name, the report pulls in multiple entries per patient with varying scores - and since duplicate entries are not always adjacent, I can't use Previous or Next to suppress them. To fix this, I'd like to only display the latest entry for each patient based on the Assessment Date field - while maintaining the above order.
I'm convinced this behavior can be implemented with a custom SQL command to only pull in the latest entry per patient, but have had no success creating that behavior myself. How can I accomplish this compound sort?
Current SQL Statement in use:
SELECT "EpisodeSummary"."PatientID",
"EpisodeSummary"."Patient_Name",
"EpisodeSummary"."Program_Value"
"RiskRating"."Rating_Period",
"RiskRating"."Assessment_Date",
"RiskRating"."Episode_Number",
"RiskRating"."PatientID",
"Facility"."Provider_Name",
FROM (
"SYSTEM"."EpisodeSummary"
"EpisodeSummary"
LEFT OUTER JOIN "FOOBARSYSTEM"."RiskAssessment" "RiskRating"
ON (
("EpisodeSummary"."Episode_Number"="RiskRating"."Episode_Number")
AND
("EpisodeSummary"."FacilityID"="RiskRating"."FacilityID")
)
AND
("EpisodeSummary"."PatientID"="RiskRating"."PatientID")
), "SYSTEM"."Facility" "Facility"
WHERE (
"EpisodeSummary"."FacilityID"="Facility"."FacilityID"
)
AND "RiskRating"."PatientID" IS NOT NULL
ORDER BY "EpisodeSummary"."Program_Value"
The SQL code below may not be exactly correct, depending on the structure of your tables. The code below assumes the 'duplicate risk scores' were coming from the RiskAssessment table. If this is not correct, the code may need to be altered.
Essentially, we create a derived table and create a row_number for each record, based on the patientID and ordered by the assessment date - The most recent date will have the lowest number (1). Then, on the join, we restrict the resultset to only select record #1 (each patient has its own rank #1).
If this doesn't work, let me know and provide some table details -- Should the Facility table be the starting point? are there multiple entries in EpisodeSummary per patient? thanks!
SELECT es.PatientID
,es.Patient_Name
,es.Program_Value
,rrd.Rating_Period
,rrd.Assessment_Date
,rrd.Episode_Number
,rrd.PatientID
,f.Provider_Name
FROM SYSTEM.EpisodeSummary es
LEFT JOIN (
--Derived Table retreiving highest risk score for each patient)
SELECT PatientID
,Assessment_Date
,Episode_Number
,FacilityID
,Rating_Period
,ROW_NUMBER() OVER (
PARTITION BY PatientID ORDER BY Assessment_Date DESC
) AS RN -- This code generates a row number for each record. The count is restarted for every patientID and the count starts at the most recent date.
FROM RiskAssessment
) rrd
ON es.patientID = rrd.patientid
AND es.episode_number = rrd.episode_number
AND es.facilityid = rrd.facilityid
AND rrd.RN = 1 --This only retrieves one record per patient (the most recent date) from the riskassessment table
INNER JOIN SYSTEM.Facility f
ON es.facilityid = f.facilityid
WHERE rrd.PatientID IS NOT NULL
ORDER BY es.Program_Value
I have a database which consists of employees (one table) which can be assigned to groups (another table). Bother are joined together with another table, employee-to-group, which lists the group id, the employee id and the start date of the assignment.
An employee always has to be assigned to a group, but the assignments can change daily. One employee could be working in group A for day, then change into group B and work in group C only a week later.
My task is to find out which employees are assigned to a certain group given by its name at any given date. So the input should be: group name, date and I want the output to be the data of all the employees which are part of that group at the given moment in time.
Here's an SQL fiddle with some test data:
http://sqlfiddle.com/#!9/6d0bb
I recreated the database with mysql-statements because I couldn't figure out the oracle statements, I'm sorry.
As you can see from the test data, some employees may never change groups, while others change frequently. THere are also employees which are planned to change assignments in the future. The query has to account for that.
Because the application is a legacy one, the values (especially in the date field) are questionable. They are given as "days since the 1st of january, 1990", so the entry "9131" means "1st of january, 2015". 9468 would be today (2015-12-04) and 9496 would be 2016-01-01).
What I already have is code to find out the "date value" for any given date in what I call the "legacy format" of the application I'm working with (here I've just used CURRENT_DATE):
SELECT FLOOR(CURRENT_DATE - TO_DATE('1990-01-01', 'YYYY-MM-DD')) AS diffdate
For finding out which group a certain employee is assigned to, I tried:
SELECT * FROM history h
WHERE emp_nr = 1 AND valid_from <= 9131
ORDER BY valid_from DESC
FETCH FIRST ROW ONLY;
which should return me the group which an employee is assigned to on the 1st of january 2015.
What I do need help with is creating a statement that joins all tables does the same for a whole group instead of only one employee (as there are thousands of employees in the database and I only want the data of at most 10 groups).
I'm thankful for any kind of pointers in the right direction.
Use row_number to rank your history and get the latest group, just as you did with your FETCH FIRST query:
select *
from
(
select
h.*,
row_number() over (partition by emp_nr order by valid_from desc) as rn
from history h
where valid_from <= 9131
)
where rn = 1
You can then join this result with other tables.