I have the following queries:
1
SELECT TOP 1
CASE WHEN latency=-1
THEN 'Down'
ELSE 'Up'
END AS status
FROM
#pings_temp
ORDER BY datetime DESC;
2
SELECT TOP 1
CASE WHEN latency=-1
THEN 'Down'
ELSE 'Up'
END AS status,
CASE WHEN latency=-1
THEN
(
SELECT TOP 1
datetime
FROM
#downtimes_temp
ORDER BY
datetime DESC
)
ELSE NULL
END AS datetime
FROM
#pings_temp
ORDER BY datetime DESC;
The first should yield just 'Up' and the second should yield 'Up' in the first column and NULL in the second.
However, this doesn't happen. The first query performs exactly how it should, but adding the second column to the SELECT makes the query go berserk, causing it to read out 'Down' and the date from a seemingly random column.
Here's an image of the two results from the same T-SQL batch.
The error in the second case is probably caused by your ORDER BY clause, since the engine cannot evaluate the order of a NULL value.
Related
I am trying to understand how to group values together to add an indicator. I want to 'fix' the values and based on this, attribute an indicator.
The values I am trying to group are date, customer name and product type to create an indicator which captures what kind of order was placed (fruit only, fruit and vegetable, vegetable only). The goal is to calculate the total volume of each kind of order placed. The data is set out like this, and the column I am trying to create is the 'Order Type.
What I have done so far:
I originally completed this analysis in Tableau ]where I was able to use the 'Fixed' function and sum the value of indicators (for fruit or veggie) to determine each order type individually.
I have written case statements to identify the product type, with the idea that I could sum this to determine order type (code below) however this did not work as I only need one instance of the indicator for each order. To solve this, I have written a case statement which partitions the fields and orders by date to get one instance of an indicator for each order.
Case Statements
CASE WHEN Product_Type = 'Fruit' THEN 1 ELSE 0 END AS Fruit_Indicator
, CASE WHEN Product_Type = 'Vegetable' THEN 1 ELSE 0 END AS Veg_Indicator
Case Statement with partition by and order by
, CASE WHEN ROW_NUMBER() OVER (PARTITION BY Order_Date, Customer ORDER BY Order_Date ASC) = 1 AND Product_Type = 'Fruit' THEN 1 ELSE NULL END AS Fruit_Ind
, CASE WHEN ROW_NUMBER() OVER (PARTITION BY Order_Date, Customer ORDER BY Order_Date ASC) = 1 AND Product_Type = 'Vegetable' THEN 1 ELSE NULL END AS Veg_Ind
I would appreciate any guidance on the right direction.
Thanks!
It APPEARS you are trying to get data grouped by date such as Mar 21, Mar 22, etc... So, you may want to have a secondary query to join the primary data from. The second query will be an aggregate by customer and date. If the date field is date/time oriented, you will have to adjust the group by to get proper formatted context such as date-format using month/day/year and ignoring any time component. This might also be handled by a function to just get the date-part and ignoring the time. Then, your original data to the aggregate should get you what you need. Maybe something like.
select
yt.date,
yt.customer,
yt.product,
yt.productType,
case when PreQuery.IsFruit > 0 and PreQuery.IsVegetable > 0
then 'Fruit & Vegetable'
when PreQuery.IsFruit > 0 and PreQuery.IsVegetable = 0
then 'Fruit Only'
when PreQuery.IsFruit = 0 and PreQuery.IsVegetable > 0
then 'Vegetable Only' end OrderType
from
YourTable yt
JOIN
( select
yt2.customer,
yt2.date,
max( case when yt2.ProductType = 'Fruit'
then 1 else 0 end ) IsFruit,
max( case when yt2.ProductType = 'Vegetable'
then 1 else 0 end ) IsVegetable
from
YourTable yt2
-- if you want to restrict time period, add a where
-- clause here on the date range as to not query entire table
group by
yt2.customer,
yt2.date ) PreQuery
ON yt.customer = PreQuery.customer
AND yt.date = PreQuery.date
-- same here for your outer query to limit just date range in question.
-- if you want to restrict time period, add a where
-- clause here on the date range as to not query entire table
order by
yt.date,
yt.customer,
yt.product
I am trying to write subselect which will run through returned data, then checks status of all and then decides uniquity logic.
Is there any way to find out following ?
case any of data has 'Active' status first one will be marked as 1 everything else as 0
case there is no 'Active' status then first 'Expired' status will by marked as 1 and everything else as 0
case there is no 'Active' and 'Expired' status then first 'In Progress' will be marked as 1 and everything else as 0
I was trying to write it like this but i need to have it in one case statement
SELECT a.id, a.status,
,(SELECT
CASE WHEN b.STATUS = 'Active' THEN 1 ELSE 0 END
CASE WHEN b.STATUS = 'Expired' THEN 1 ELSE 0 END
FROM b.TABLE
WHERE a.id=b.id )AS unique
FROM my.TABLE
Result should look like https://i.stack.imgur.com/qCA74.png picture for expired case
Thank you in advance for any tips.
Use a window function:
select t.*,
(case when row_number() over (partition by id
order by case status when 'Active' then 1 when 'Expired' then 2 else 3 end
) = 1
then 1 else 0
end) as unique_flag
from my.table t;
If the lookup table is the same as source table, then you can use LAG function with constant and use its default value to mark the first row with 1 and others with 0. But you need to order your rows by some fields to deal with duplicates on status.
select a.id, a.status,
lag(0, 1, 1) over(
partition by a.id
order by
case a.status
when 'Active' then 0
when 'Expired' then 1
else 3
end asc,
a.some_more_columns asc /*To find that first row when there are duplicates by status*/
) as unique_flag
from MY_TABLE a
And what about object naming: never use keywords as identifiers. Calling column with date as date, table with users as users and some unknown table as table makes you design error prone.
I have a query like:
select nvl(nvl(sum(a.quantity),0)-nvl(cc.quantityCor,0),0)
from RCV_TRANSACTIONS a
LEFT JOIN (select c.shipment_line_id,c.oe_order_line_id,nvl(sum(c.quantity),0) quantityCor
from RCV_TRANSACTIONS c
where c.TRANSACTION_TYPE='CORRECT'
group by c.shipment_line_id,c.oe_order_line_id) cc on (a.shipment_line_id=cc.shipment_line_id and a.shipment_line_id=7085740)
where a.transaction_type='DELIVER'
and a.shipment_line_id=7085740
group by nvl(cc.quantityCor,0);
The query runs OK, but returns no value. I want it to return 0 if there is no quantity found. Where have I gone wrong?
An aggregation query with a GROUP BY returns no rows if all rows are filtered out.
An aggregation query with no GROUP BY always returns one row, even if all rows are filtered out.
So, just remove the GROUP BY. And change the SELECT to:
select coalesce(sum(a.quantity), 0) - coalesce(max(cc.quantityCor), 0)
I may be wrong, but it seems you merely want to subtract CORRECT quantity from DELIVER quantity for shipment 7085740. You don't need a complicated query for that. Especially your GROUP BY clauses make no sense if that is what you are after.
One way to write this query would be:
select
sum(case when transaction_type = 'DELIVER' then quantity else 0 end) -
sum(case when transaction_type = 'CORRECT' then quantity else 0 end) as diff
from rcv_transactions
where shipment_line_id = 7085740;
I had a query like this and was trying to return 'X' when the item is not valid.
SELECT case when segment1 is not null then segment1 else 'X' end
--INTO v_orgValidItem
FROM mtl_system_items_b
WHERE segment1='1676001000'--'Jul-00'--l_item
and organization_id=168;
..but it was returning NULL.
Changed to use aggregation with no group by and now it returns 'X' when the item is not valid.
SELECT case when max(segment1) is not null then max(segment1) else 'X' end valid
--INTO v_orgValidItem
FROM mtl_system_items_b
WHERE segment1='1676001000'--'Jul-00'--l_item
and organization_id=168;--l_ship_to_organization_id_pb;
Here is another example, proving the order of operations really matters.
When there is no match for this quote number, this query returns NULL:
SELECT MAX(NVL(QUOTE_VENDOR_QUOTE_NUMBER,0))
FROM PO_HEADERS_ALL
WHERE QUOTE_VENDOR_QUOTE_NUMBER='foo.bar';
..reversing the order of MAX and NVL makes all the difference. This query returns the NULL value condition:
SELECT NVL(MAX(QUOTE_VENDOR_QUOTE_NUMBER),0)
FROM PO_HEADERS_ALL
WHERE QUOTE_VENDOR_QUOTE_NUMBER='foo.bar';
I am testing ORDER BY clause with CASE, and came across this problem.
My test select statement:
SELECT to_date as "One", field1 as "Two"
FROM(
SELECT to_date('yyyy-mm-dd', '2017-10-10'), '333' union all
SELECT to_date('yyyy-mm-dd', '2017-09-09'), '111' union all
SELECT to_date('yyyy-mm-dd', '2017-09-09'), '222' union all
SELECT to_date('yyyy-mm-dd', '2017-09-09'), '' union all
SELECT to_date('yyyy-mm-dd', '2017-09-09'), ''
)
ORDER BY One DESC,
CASE when Two = '' then 1
else 0 end DESC
And it's result may vary in a way, that sorting by second column is random:
How should I modify CASE clause to avoid it?
In Oracle, an empty string '' is the identical to NULL so your query is:
ORDER BY
One DESC,
CASE when Two = NULL then 1 else 0 end DESC
When comparing values, the are possible states are:
Equality Result
------------------------ ------
value = value TRUE
value = other_value FALSE
value = NULL NULL
NULL = NULL NULL
Your CASE expression will only evaluate to 1 when the equality evaluates to TRUE and this will never be the result when at least one side of the equality is NULL.
What you want is to use IS NULL rather than = '':
ORDER BY
One DESC,
CASE WHEN Two IS NULL THEN 1 ELSE 0 END DESC,
Two DESC;
Which you can simplify to:
ORDER BY
One DESC,
Two DESC NULLS FIRST;
The default for DESC ordering is NULLS FIRST so you could further simplify it to:
ORDER BY
One DESC,
Two DESC;
However, I would not take it this far as you are better explicitly stating that you are expecting NULL values to be ordered before non-NULL so future developers know that that is your intended ordering (rather than just an unintentional side-effect of your query).
Add the column two as third order condition
ORDER BY One DESC,
CASE when Two = '' then 1 else 0 end DESC,
Two DESC
The second order condition only puts empty entries first and not more.
I have this SQL statement that sorts the rows depending on their change_order and change_id.
My statement looks like this:
select *
from change_dtl_from2
where chnfr_hdrno = 'CH000009'
order by
case
when chnorder is null
then 1
else 0
end asc, change_id asc
Where chnfr_hdrno is the document number, chnorder is change_order, change_id is unique key per row.
If I execute that statement, the result will be like this:
As you can see, the row with chnorder value of 5 is on the top most where the chnorder is set its order by ascending. I don't know where or what I'm doing wrong.
The default value of chnorder is null and is an int column. That's why I'm confused because whenever I add a new row, the new one will be on top most. I hope you can all help me. :)
SQL does everything correct depending on your query. With your CASE-Statement you "replace" all non-NULL-values to 1 and sort them only by change_id. If you only want to replace NULL by 1 you should use
order by (case when chnorder is null then 1 else chnordner end) asc
or you should use
order by (case when chnorder is null then 1 else 0 end) asc, chnordner asc, change_id asc