I am running this query
Playlistship.order("created_at desc").select("distinct playlist_id").limit(12).offset(2)
This query does not necessarily return 12 records. It returns the number of distinct records in the set of 12 defined by the LIMIT, OFFSET and ORDER parameters.
For example if the Playlistships between id=13 and id=24 had playlist_ids of [2,3,3,5,6,3,5,6,8,11,12,12], then this query will only give return 7 records, corresponding to the first ones having the playlist_ids [2,3,5,6,8,11,12].
What I would like to find is a query that yields 12, records with distinct playlist_ids, with the correct offset so that running this query again with an OFFSET of 3 would yield the next 12 records with distinct playlist_ids.
Hopefully I didn't "over explain" this one, as I think it's a relatively straightforward question. Please ask for more details if you need them.
Thanks!
Have you tried with subqueries? Give this a try:
Playlistship.select("distinct playlist_id").limit(12).where(playlist_id: Playlistship.order("created_at desc").select('playlist_id').offset(2))
Related
I can't seem to figure out how to combine the result of 2 Business Objects queries.
Both queries return a set of codes and a number of hours. Query 1 can have codes that do not appear in Query 2, and Query 2 can have codes that do not appear in Query 1.
The resulting report should contain all codes from both Query 1 and Query2, a column with the sum of hours from Q1 for that code, and a column with the sum of hours from Query 2 for that code. If one of the queries doesn't have a code in it, it would return a blank or 0 total.
Example:
Q1 results:
|Code|Value|
|:---|:----|
|A|15|
|A|17|
|B|12|
|D|22|
|D|35|
|E|16|
|E|9|
|E|11|
Q2 results:
|Code|Value|
|:---|:----|
|A|5|
|A|19|
|B|33|
|C|17|
|C|24|
|E|78|
|E|12|
Report:
|Code|Value1|Value2|
|----|------|------|
|A|32|24|
|B|12|33|
|C| |41|
|D|57| |
|E|36|90|
|Total|137|188|
When I create the Business Object report table as normal, only the values of Query 1 are used, and I miss the row for value C. If I flip the queries around, I miss the row for value D.
How do I set up my report to show all the code values?
Edit: Sorry for the formatting of the tables, in the preview it looks perfect. :(
I have a clickhouse table that has one Array(UInt16) column. I want to be able to filter results from this table to only get rows where the values in the array column are above a threshold value. I've been trying to achieve this using some of the array functions (arrayFilter and arrayExists) but I'm not familiar enough with the SQL/Clickhouse query syntax to get this working.
I've created the table using:
CREATE TABLE IF NOT EXISTS ArrayTest (
date Date,
sessionSecond UInt16,
distance Array(UInt16)
) Engine = MergeTree(date, (date, sessionSecond), 8192);
Where the distance values will be distances from a certain point at a certain amount of seconds (sessionSecond) after the date. I've added some sample values so the table looks like the following:
Now I want to get all rows which contain distances greater than 7. I found the array operators documentation here and tried the arrayExists function but it's not working how I'd expect. From the documentation, it says that this function "Returns 1 if there is at least one element in 'arr' for which 'func' returns something other than 0. Otherwise, it returns 0". But when I run the query below I get three zeros returned where I should get a 0 and two ones:
SELECT arrayExists(
val -> val > 7,
arrayEnumerate(distance))
FROM ArrayTest;
Eventually I want to perform this select and then join it with the table contents to only return rows that have an exists = 1 but I need this first step to work before that. Am I using the arrayExists wrong? What I found more confusing is that when I change the comparison value to 2 I get all 1s back. Can this kind of filtering be achieved using the array functions?
Thanks
You can use arrayExists in the WHERE clause.
SELECT *
FROM ArrayTest
WHERE arrayExists(x -> x > 7, distance) = 1;
Another way is to use ARRAY JOIN, if you need to know which values is greater than 7:
SELECT d, distance, sessionSecond
FROM ArrayTest
ARRAY JOIN distance as d
WHERE d > 7
I think the reason why you get 3 zeros is that arrayEnumerate enumerates over the array indexes not array values, and since none of your rows have more than 7 elements arrayEnumerates results in 0 for all the rows.
To make this work,
SELECT arrayExists(
val -> distance[val] > 7,
arrayEnumerate(distance))
FROM ArrayTest;
I'm attempting to make a linq where contains query quicker.
The data set contains 256,999 clients. The Ids is just a simple list of GUID'S and this would could only contain 3 records.
The below query can take up to a min to return the 3 records. This is because the logic will go through the 256,999 record to see if any of the 256,999 records are within the List of 3 records.
returnItems = context.ExecuteQuery<DataClass.SelectClientsGridView>(sql).Where(x => ids.Contains(x.ClientId)).ToList();
I would like to and get the query to check if the three records are within the pot of 256,999. So in a way this should be much quicker.
I don't want to do a loop as the 3 records could be far more (thousands). The more loops the more hits to the db.
I don't want to grap all the db records (256,999) and then do the query as it would take nearly the same amount of time.
If I grap just the Ids for all the 256,999 from the DB it would take a second. This is where the Ids come from. (A filtered, small and simple list)
Any Ideas?
Thanks
You've said "I don't want to grab all the db records (256,999) and then do the query as it would take nearly the same amount of time," but also "If I grab just the Ids for all the 256,999 from the DB it would take a second." So does this really take "just as long"?
returnItems = context.ExecuteQuery<DataClass.SelectClientsGridView>(sql).Select(x => x.ClientId).ToList().Where(x => ids.Contains(x)).ToList();
Unfortunately, even if this is fast, it's not an answer, as you'll still need effectively the original query to actually extract the full records for the Ids matched :-(
So, adding an index is likely your best option.
The reason the Id query is quicker is due to one field being returned and its only a single table query.
The main query contains sub queries (below). So I get the Ids from a quick and easy query, then use the Ids to get the more details information.
SELECT Clients.Id as ClientId, Clients.ClientRef as ClientRef, Clients.Title + ' ' + Clients.Forename + ' ' + Clients.Surname as FullName,
[Address1] ,[Address2],[Address3],[Town],[County],[Postcode],
Clients.Consent AS Consent,
CONVERT(nvarchar(10), Clients.Dob, 103) as FormatedDOB,
CASE WHEN Clients.IsMale = 1 THEN 'Male' WHEN Clients.IsMale = 0 THEN 'Female' END As Gender,
Convert(nvarchar(10), Max(Assessments.TestDate),103) as LastVisit, ";
CASE WHEN Max(Convert(integer,Assessments.Submitted)) = 1 Then 'true' ELSE 'false' END AS Submitted,
CASE WHEN Max(Convert(integer,Assessments.GPSubmit)) = 1 Then 'true' ELSE 'false' END AS GPSubmit,
CASE WHEN Max(Convert(integer,Assessments.QualForPay)) = 1 Then 'true' ELSE 'false' END AS QualForPay,
Clients.UserIds AS LinkedUsers
FROM Clients
Left JOIN Assessments ON Clients.Id = Assessments.ClientId
Left JOIN Layouts ON Layouts.Id = Assessments.LayoutId
GROUP BY Clients.Id, Clients.ClientRef, Clients.Title, Clients.Forename, Clients.Surname, [Address1] ,[Address2],[Address3],[Town],[County],[Postcode],Clients.Consent, Clients.Dob, Clients.IsMale,Clients.UserIds";//,Layouts.LayoutName, Layouts.SubmissionProcess
ORDER BY ClientRef
I was hoping there was an easier way to do the Contain element. As the pool of Ids would be smaller than the main pool.
A way I've speeded it up for now is. I've done a Stinrg.Join to the list of Ids and added them as a WHERE within the main SQL. This has reduced the time down to a seconds or so now.
I am using the Ruby Mongoid gem and trying to create a query to retrieve the last 100 documents from a collection. Rather than using Mongoid, I would like to create the query using the underlying driver (Moped). The Moped documentation only mentions how to retrieve the first 100 records:
session[:my_collection].find.limit(100)
How can I retrieve the last 100?
I have found a solution, but you will need to sort collection in descending order. If you have a field id or date you would do:
Method .sort({fieldName: 1 or -1})
The 1 will sort ascending (oldest to newest), -1 will sort descending (newest to oldest). This will reverse entries of your collection.
session[:my_collection].find().sort({id:-1}) or
session[:my_collection].find().sort({date:-1})
If your collection contain field id (_id) that identifier have a date embedded, so you can use
session[:my_collection].find().sort({_id:-1})
In accordance with your example using .limit() the complete query will be:
session[:my_collection].find().sort({id:-1}).limit(100);
Technically that query isn't finding the first 100, that's essentially finding 100 random documents because you haven't specified an order. If you want the first then you'd have to say explicitly sort them:
session[:my_collection].find.sort(:some_field => 1).limit(100)
and to reverse the order to find the last 100 with respect to :some_field:
session[:my_collection].find.sort(:some_field => -1).limit(100)
# -----------------------------------------------^^
Of course you have decide what :some_field is going to be so the "first" and "last" make sense for you.
If you want them sorted by :some_field but want to peel off the last 100 then you could reverse them in Ruby:
session[:my_collection].find
.sort(:some_field => -1)
.limit(100)
.reverse
or you could use use count to find out how many there are then skip to offset into the results:
total = session[:my_collection].find.count
session[:my_collection].find
.sort(:some_field => 1)
.skip(total - 100)
You'd have to check that total >= 100 and adjust the skip argument if it wasn't of course. I suspect that the first solution would be faster but you should benchmark it with your data to see what reality says.
I have the following SOQL query to display List of ABCs in my Page block table.
Public List<ABC__c> getABC(){
List<ABC__c> ListABC = [Select WB1__c, WB2__c, WB3__c, Number, tentative__c, Actual__c, PrepTime__c, Forecast__c from ABC__c ORDER BY WB3__c];
return ListABC;
}
As you can see in the above image, WB3 has number of records for A, B and C. But I want to display only 1 record for each WB3 group based on Actual__c. Only latest Actual__c must be displayed for each WB3 Group.
i.e., Ideally I want to display only 3 rows(one each for A,B,C) in this example.
For this, I have used GROUPBY and displayed the result using AggregateResults. Here is the result.
I got the Latest Actual Date for each WB3 as shown above. But the Tentative date is not corresponding to it. The Tentative Date is also the MAX in the list.
Here is the code I used
public List<SiteMonitoringOverview> getSPM(){
AggregateResult[] AgR = [Select WB_3__c, MAX(Tentaive_Date__c) dtTentativeDate , MAX(Actual_Date__c) LatestCDate FROM Site_progress_Monitoring__c GROUP BY WBS_3__c];
if(AgR.size()>0){
for(AggregateResult SalesList : AgR){
CustSumList.add(new SiteMonitoringOverview(String.ValueOf(SalesList.get('WB_3__c')), String.valueOf(SalesList.get('dtTentativeDate')), String.valueOF(SalesList.get('LatestCDate')) ));
}
}
return CustSumList;
}
I am forced to use MAX() for tentative date. I want the corresponding Tentative date of the MAX Actual Date. Not the Max Tentative Date.
For group A, the Tentative Date of Max Actual Date is 12/09/2012. But it is displaying the MAX tentative date: 27/02/2013. It should display 12/09/2012. This is because I am using MAX(Tentative_Date__c) in my code. Every column in the SOQL query must be either GROUPED or AGGREGATED. That's weird.
How do I get the required 3 rows in this example?
Any suggestions? Any different approach (looping within in groups)? how?
Just ran into this issue myself. The solution I came up with only works if you want the oldest or newest record from each grouping. Unfortunately it probably won't work in your case. I'll still leave this here incase it does happen to help someone searching for a solution to this issue.
AggregateResult[] groupedResults = [Select Max(Id), WBS_3__c FROM Site_progress_Monitoring__c GROUP BY WBS_3__c];
Calling MAX or MIN on the Id will let you get 1 record per group condition. You can then query other information. I my case I just need 1 record from each group and didn't really care which one it was.