I need to order by 2 fields:
SELECT * FROM item ORDER BY date ASC, sequence DESC;
Is it possible to emulate this SQL with Squeryl?
You can order by multiple fields. Just add them to the orderByclause as below:
from(table)(t => select(t) orderBy(t.date, t.sequence desc)
Related
I have one table where multiple records inserted for each group of product. Now, I want to extract (SELECT) only the last entries. For more, see the screenshot. The yellow highlighted records should be return with select query.
The HAVING MAX and HAVING MIN clause for the ANY_VALUE function is now in preview
HAVING MAX and HAVING MIN were just introduced for some aggregate functions - https://cloud.google.com/bigquery/docs/release-notes#February_06_2023
with them query can be very simple - consider below approach
select any_value(t having max datetime).*
from your_table t
group by t.id, t.product
if applied to sample data in your question - output is
You might consider below as well
SELECT *
FROM sample_table
QUALIFY DateTime = MAX(DateTime) OVER (PARTITION BY ID, Product);
If you're more familiar with an aggregate function than a window function, below might be an another option.
SELECT ARRAY_AGG(t ORDER BY DateTime DESC LIMIT 1)[SAFE_OFFSET(0)].*
FROM sample_table t
GROUP BY t.ID, t.Product
Query results
You can use window function to do partition based on key and selecting required based on defining order by field.
For Example:
select * from (
select *,
rank() over (partition by product, order by DateTime Desc) as rank
from `project.dataset.table`)
where rank = 1
You can use this query to select last record of each group:
Select Top(1) * from Tablename group by ID order by DateTime Desc
In SQL 2005/2008 database we have table BatchMaster. Columns:
RecordId bigint - autoincremental id, BatchNumber bigint - unique non-clustered index, BatchDate). We have sproc that returns paginated data from this table. That sproc works fine for most of the clients, but at one SQL server instance we have problem with records order.
In general, at sproc we do
select * from
(
select row_number() over (order by bm.BatchDate desc, bm.BatchNumber desc) as Row,
*
from dbo.BatchMaster bm with (nolock)
)
where Row between #StartingRow and #EndgingRow
So, as you can notice from the script above we want return records sorted by BatchDate and BatchNumber. That's not gonna happen for one of our client:
Records are in wrong order. Also, notice first column (Row), it is not in ascending order.
Can someone explain why so?
Assuming you want the lowest BatchNumber for a given BatchDate with the smallest Row number and that you want orderer by the Row, try this:
select * from
(
select row_number() over (order by bm.BatchDate desc, bm.BatchNumber asc) as Row,
*
from dbo.BatchMaster bm with (nolock)
)
where Row between #StartingRow and #EndgingRow
order by Row
Your code doesn't actually sort the results, it only sets 'Row' based on the order of BatchDate and Batchnumber and appears to be doing that correctly. You need to add ORDER BY Row to your statement.
Change your query to include a sort in the outermost query
select * from
(
select row_number() over (order by bm.BatchDate desc, bm.BatchNumber desc) as Row,
*
from dbo.BatchMaster bm with (nolock)
)
where Row between #StartingRow and #EndgingRow
order by Row
The ORDER BY clause in your ROW_NUMBER ranking function only applies to calculating the value of that ranking function, it does not actually order the results.
If you would like the records returned in a certain order you will need specify that in your query: ORDER BY [Row]
I use this SQL to grab some indexes:
select follow
from unigram
where alternativeSpelling like 'test'
order by freq desc
limit 10;
I then convert them to words using this SQL, one by one:
select word
from wordIdxTranslate
where word_idx = <one of the indexes from above>
How do I combine these to a single query, whil epreserving the ranking order from the first query ("freq")?
Untested, but this should do it:
SELECT word
FROM unigram, wordIdxTranslate
WHERE
unigram.follow=wordIdxTranslate.word_idx
AND
unigram.follow IN (SELECT T1.follow
FROM unigram AS T1
WHERE T1.alternativeSpelling LIKE 'test'
ORDER BY T1.freq DESC
LIMIT 10)
ORDER BY freq DESC
One option would be to combine the queries with a join, like:
select word
from (
select follow
, freq
from unigram
where alternativeSpelling like 'test'
order by
freq desc
limit 10
) uni
join wordIdxTranslate wit
on wit.word_idx = uni.follow
order by
uni.freq desc
After executing the following statement:
SELECT Category FROM MonitoringJob ORDER BY CreationDate DESC
I am getting the following values from the database:
test3
test3
bildung
test4
test3
test2
test1
but I want the duplicates removed, like this:
bildung
test4
test3
test2
test1
I tried to use DISTINCT but it doesn't work with ORDER BY in one statement. Please help.
Important:
I tried it with:
SELECT DISTINCT Category FROM MonitoringJob ORDER BY CreationDate DESC
it doesn't work.
Order by CreationDate is very important.
The problem is that the columns used in the ORDER BY aren't specified in the DISTINCT. To do this, you need to use an aggregate function to sort on, and use a GROUP BY to make the DISTINCT work.
Try something like this:
SELECT DISTINCT Category, MAX(CreationDate)
FROM MonitoringJob
GROUP BY Category
ORDER BY MAX(CreationDate) DESC, Category
Extended sort key columns
The reason why what you want to do doesn't work is because of the logical order of operations in SQL, as I've elaborated in this blog post, which, for your first query, is (simplified):
FROM MonitoringJob
SELECT Category, CreationDate i.e. add a so called extended sort key column
ORDER BY CreationDate DESC
SELECT Category i.e. remove the extended sort key column again from the result.
So, thanks to the SQL standard extended sort key column feature, it is totally possible to order by something that is not in the SELECT clause, because it is being temporarily added to it behind the scenes.
So, why doesn't this work with DISTINCT?
If we add the DISTINCT operation, it would be added between SELECT and ORDER BY:
FROM MonitoringJob
SELECT Category, CreationDate
DISTINCT
ORDER BY CreationDate DESC
SELECT Category
But now, with the extended sort key column CreationDate, the semantics of the DISTINCT operation has been changed, so the result will no longer be the same. This is not what we want, so both the SQL standard, and all reasonable databases forbid this usage.
Workarounds
It can be emulated with standard syntax as follows
SELECT Category
FROM (
SELECT Category, MAX(CreationDate) AS CreationDate
FROM MonitoringJob
GROUP BY Category
) t
ORDER BY CreationDate DESC
Or, just simply (in this case), as shown also by Prutswonder
SELECT Category, MAX(CreationDate) AS CreationDate
FROM MonitoringJob
GROUP BY Category
ORDER BY CreationDate DESC
I have blogged about SQL DISTINCT and ORDER BY more in detail here.
If the output of MAX(CreationDate) is not wanted - like in the example of the original question - the only answer is the second statement of Prashant Gupta's answer:
SELECT [Category] FROM [MonitoringJob]
GROUP BY [Category] ORDER BY MAX([CreationDate]) DESC
Explanation: you can't use the ORDER BY clause in an inline function, so the statement in the answer of Prutswonder is not useable in this case, you can't put an outer select around it and discard the MAX(CreationDate) part.
Just use this code, If you want values of [Category] and [CreationDate] columns
SELECT [Category], MAX([CreationDate]) FROM [MonitoringJob]
GROUP BY [Category] ORDER BY MAX([CreationDate]) DESC
Or use this code, If you want only values of [Category] column.
SELECT [Category] FROM [MonitoringJob]
GROUP BY [Category] ORDER BY MAX([CreationDate]) DESC
You'll have all the distinct records what ever you want.
2) Order by CreationDate is very important
The original results indicated that "test3" had multiple results...
It's very easy to start using MAX all the time to remove duplicates in Group By's... and forget or ignore what the underlying question is...
The OP presumably realised that using MAX was giving him the last "created" and using MIN would give the first "created"...
if object_id ('tempdb..#tempreport') is not null
begin
drop table #tempreport
end
create table #tempreport (
Category nvarchar(510),
CreationDate smallint )
insert into #tempreport
select distinct Category from MonitoringJob (nolock)
select * from #tempreport ORDER BY CreationDate DESC
Distinct will sort records in ascending order. If you want to sort in desc order use:
SELECT DISTINCT Category
FROM MonitoringJob
ORDER BY Category DESC
If you want to sort records based on CreationDate field then this field must be in the select statement:
SELECT DISTINCT Category, creationDate
FROM MonitoringJob
ORDER BY CreationDate DESC
You can use CTE:
WITH DistinctMonitoringJob AS (
SELECT DISTINCT Category Distinct_Category FROM MonitoringJob
)
SELECT Distinct_Category
FROM DistinctMonitoringJob
ORDER BY Distinct_Category DESC
By subquery, it should work:
SELECT distinct(Category) from MonitoringJob where Category in(select Category from MonitoringJob order by CreationDate desc);
We can do this with select sub query
Here is the the query:
SELECT * FROM (
SELECT DISTINCT Category FROM MonitoringJob
) AS Tbl
ORDER BY Tbl.CreationDate DESC
Try next, but it's not useful for huge data...
SELECT DISTINCT Cat FROM (
SELECT Category as Cat FROM MonitoringJob ORDER BY CreationDate DESC
);
It can be done using inner query Like this
$query = "SELECT *
FROM (SELECT Category
FROM currency_rates
ORDER BY id DESC) as rows
GROUP BY currency";
SELECT DISTINCT Category FROM MonitoringJob ORDER BY Category ASC
I have a query where I wish to retrieve the oldest X records. At present my query is something like the following:
SELECT Id, Title, Comments, CreatedDate
FROM MyTable
WHERE CreatedDate > #OlderThanDate
ORDER BY CreatedDate DESC
I know that normally I would remove the 'DESC' keyword to switch the order of the records, however in this instance I still want to get records ordered with the newest item first.
So I want to know if there is any means of performing this query such that I get the oldest X items sorted such that the newest item is first. I should also add that my database exists on SQL Server 2005.
Why not just use a subquery?
SELECT T1.*
FROM
(SELECT TOP X Id, Title, Comments, CreatedDate
FROM MyTable
WHERE CreatedDate > #OlderThanDate
ORDER BY CreatedDate) T1
ORDER BY CreatedDate DESC
Embed the query. You take the top x when sorted in ascending order (i.e. the oldest) and then re-sort those in descending order ...
select *
from
(
SELECT top X Id, Title, Comments, CreatedDate
FROM MyTable
WHERE CreatedDate > #OlderThanDate
ORDER BY CreatedDate
) a
order by createddate desc