I want to generate a sequence for a complex query. For that purpose I have used a variable #rowNo.
My logic is :-
If a field - isremoved = 0 then increase row number by 1.
If isremoved = 1 then increase row number by 1 only once till you find next 0.
This is so far I have done, but it gives me syntax error.
DECLARE #rowNo INT;
SET #rowNo = -1;
SELECT
case when sampleTable.isremoved = 0 then #rowNo + 1
else #rowNo end
as rowNumber,
X,
Y,
Z
.
.
FROM tbl_sample sampleTable
INNER JOIN tbl_sample_2 sample2 ON sampleTable.id = sample2.id
.
.
.
This is my desire output :-
So what is the right way to achieve this kind of functionality in sql server 2012 ?
EDIT :-
I do have one solution to use sub query to retrieve row number. But that will hit performance as it is very complex query (more than 20 joins) with huge amount of data.
So please suggest me an alternative.
In SQL Server 2012+, you can do what you want with a cumulative sum:
SELECT sum(case when sampleTable.isremoved = 0 then 1 else 0 end) over
(order by . . .)
. . .
The order by should repeat the order by in the outer query. You can also try using order by (select null)). In my experience, this uses the ordering of the data in the outer query, but this is not documented to always work.
SQL Server does not allow you to set variables in a SELECT and to return values in a result set. One or the other, but not both.
one way to do this is with subquery:
Select (Select count(*) from tbl_sample
where id <= a.id
and a.isRemoved =1) rowNumber,
X, Y, Z
From tbl_sample a
Join tbl_sample_2 b
On b.id = a.id
I assume your rowNumber logic is equivalent to: if previous isremoved = 0 then increment rowNumber by 1, otherwise keep it as it is.
Using a combination of LAG and SUM ... OVER you can easily implement this logic:
SELECT id, isremoved,
SUM(IIF(prevFlag = 0, 1, 0)) OVER (ORDER BY id) AS rowNumber
FROM (
SELECT a.id, isremoved,
COALESCE(LAG(isremoved) OVER (ORDER BY a.id), isremoved) AS prevFlag
FROM tbl_sample AS a
INNER JOIN tbl_sample_2 AS b ON b.id = a.id) AS t
Demo here
Related
There is a field in the sql query that I can't do. First of all, a new column must be added to the table below. The value of this column needs to be percent complete, so it's a percentage value. So for example, there are 7 values from Cupboard=1 shelves. Where IsCounted is here, 3 of them are counted. In other words, those with Cupboard = 1 should write the percentage value of 3/7 as the value in the new column to be created. If the IsCounted of the others is 0, it will write zero percent. How can I do this?
My Sql Code:
SELECT a.RegionName,
a.Cupboard,
a.Shelf,
(CASE WHEN ToplamSayım > 0 THEN 1 ELSE 0 END) AS IsCounted
FROM (SELECT p.RegionName,
r.Shelf,
r.Cupboard,
(SELECT COUNT(*)
FROM FAZIKI.dbo.PM_ProductCountingNew
WHERE RegionCupboardShelfTypeId = r.Id) AS ToplamSayım
FROM FAZIKI.dbo.DF_PMRegionType p
JOIN FAZIKI.dbo.DF_PMRegionCupboardShelfType r ON p.Id = r.RegionTypeId
WHERE p.WarehouseId = 45) a
ORDER BY a.RegionName;
The result is as in the picture below:
It looks like a windowed AVG should do the trick, although it's not entirely clear what the partitioning column should be.
The SELECT COUNT can be simplified to an EXISTS
SELECT a.RegionName,
a.Cupboard,
a.Shelf,
a.IsCounted,
AVG(a.IsCounted * 1.0) OVER (PARTITION BY a.RegionName, a.Cupboard) Percentage
FROM (
SELECT p.RegionName,
r.Shelf,
r.Cupboard,
CASE WHEN EXISTS (SELECT 1
FROM FAZIKI.dbo.PM_ProductCountingNew pcn
WHERE pcn.RegionCupboardShelfTypeId = r.Id
) THEN 1 ELSE 0 END AS IsCounted
FROM FAZIKI.dbo.DF_PMRegionType p
JOIN FAZIKI.dbo.DF_PMRegionCupboardShelfType r ON p.Id = r.RegionTypeId
WHERE p.WarehouseId = 45
) a
ORDER BY a.RegionName;
Say I have a table t with 2 columns:
a int
b int
I can do a query such as:
select b
from t
where b > a
and a in(1,2,3)
order by b
where 1,2,3 is provided from the outside.
Obviously, the query can return no rows. In that case, I'd like to select everything as if the query did not have the and a in(1,2,3) part. That is, I'd like:
if exists (
select b
from t
where b > a
and a in(1,2,3)
)
select b
from t
where b > a
and a in(1,2,3)
order by b
else
select b
from t
where b > a
order by b
Is there a way to do this:
Without running two queries (one for exists, the other one the actual query)
That is less verbose than repeating queries (real queries are quite long, so DRY and all that stuff)
Using NOT EXISTS with a Sub Query to Determine if condition exists
SELECT b
FROM
t
WHERE
b > a
AND (
NOT EXISTS (SELECT 1 FROM #Table WHERE a IN (1,2,3))
OR a IN (1,2,3)
)
ORDER BY
b
The reason this works is because if the condition exists then the OR statement will include the rows and if the condition does not exist then the NOT EXISTS will include ALL rows.
Or With Common Table Expression and window Function with Conditional Aggregation.
WITH cte AS (
SELECT
b
,CASE WHEN a IN (1,2,3) THEN 1 ELSE 0 END as MeetsCondition
,COUNT(CASE WHEN a IN (1,2,3) THEN a END) OVER () as ConditionCount
FROM
t
)
SELECT
b
FROM
cte
WHERE
(ConditionCount > 0 AND MeetsCondition = 1)
OR (ConditionCount = 0)
ORDER BY
b
I find it a bit "ugly". Maybe it would be better to materialize output from your query within a temp table and then based on count from temp table perform first or second query (this limits accessing the original table from 3 times to 2 and you will be able to add some flag for qualifying rows for your condition not to repeat it). Other than that, read below . . .
Though, bear in mind that EXISTS query should execute pretty fast. It stops whether it finds any row that satisfies the condition.
You could achieve this using UNION ALL to combine resultset from constrained query and full query without constraint on a column and then decide what to show depending on output from first query using CASE statement.
How CASE statement works: when any row from constrained part of your query is found, return resultset from constrainted query else return everything omitting the constraint.
If your database supports using CTE use this solution:
with tmp_data as (
select *
from (
select 'constraint' as type, b
from t
where b > a
and a in (1,2,3) -- here goes your constraint
union all
select 'full query' as type, b
from t
where b > a
) foo
)
SELECT b
FROM tmp_data
WHERE
CASE WHEN (select count(*) from tmp_data where type = 'constraint') > 0
THEN type = 'constraint'
ELSE type = 'full query'
END
;
I have the following query. I simplified it for demo purpose. I am using SQL Server - t-sql
Select tm.LocID = (select LocID from tblLoc tl
where tl.LocID = tm.LodID )
from tblMain tm
if the subquery returns multiple records, I like to assign tm.LocID to null else if there is only 1 record returned then assign it to tm.LocID. I am looking for a simple way to do this. Any help would be appreciated.
One way I can see is to have a CASE statement and check if (Count * > 1 ) then assign null else return the value but that would require a select statement within a select statement.
You have the right idea about using a case expression for count(*), but it will not require another subquery:
SELECT tm.LocID = (SELECT CASE COUNT(*) WHEN 1 THEN MAX(LocID) END
FROM tblLoc tl
WHERE tl.LocID = tm.LodID )
FROM tblMain tm
or just use a HAVING clause, like
Select tm.LocID = (select LocID from tblLoc tl
where tl.LocID = tm.LodID
group by locID
having count(*) = 1)
)
from tblMain tm
Your query above (and many of the other answers here) is a correlated subquery which will be very slow since it performs a separate aggregation query on each record. This following will address both your problem and potentially perform a bit better since the count happens in a single pass.
SELECT
CASE
WHEN x.locid IS NOT NULL THEN x.locid
ELSE NULL
END
FROM tblMain m
LEFT JOIN (
SELECT
locid
FROM tblLoc
GROUP BY locid
HAVING COUNT(1) = 1
) x
ON x.locid = m.locid
;
The above is in Postgres syntax (what I'm familiar with) so you would have to make it TSQL compatible.
I have a table of items by date (each row is a new date). I am drawing out a value from another column D. I need it to replace 0s though. I need the following logic: when D=0 for that date, use the value in column D from the date prior.
Actually, truth be told, I need it to say, when D is 0, use the value from the latest date where D was not a 0, but the first will get me most of the way there.
Is there a way to build this logic? Maybe a CTE?
Thank you very much.
PS I'm using SSMS 2008.
EDIT: I wasn't very clear at first. The value I want to change is not the date. I want change the value in D with the latest non-zero value from D, based on date.
May be the following query might help you. It uses the OUTER APPLY to fetch the results. Screenshot #1 shows the sample data and query output against the sample data. This query can be written better but this is what I could come up with right now.
Hope that helps.
SELECT ITM.Id
, COALESCE(DAT.New_D, ITM.D) AS D
, ITM.DateValue
FROM dbo.Items ITM
OUTER APPLY (
SELECT
TOP 1 D AS New_D
FROM dbo.Items DAT
WHERE DAT.DateValue < ITM.DateValue
AND DAT.D <> 0
AND ITM.D = 0
ORDER BY DAT.DateValue DESC
) DAT
Screenshot #1:
UPDATE t
Set value = SELECT value
FROM table
WHERE date = (SELECT MAX(t1.date)
FROM table t1
WHERE t1.value != 0
AND t1.date < t.date)
FROM table t
WHERE t.value = 0
You could maybe something like this as part of an update script...
SET myTable.D = (
SELECT TOP 1 myTable2.D
FROM myTable2
WHERE myTable2.myDateField < myTable.myDateField
AND myTable2.D != 0
ORDER BY myTable2.myDateField DESC)
That's assuming that you want to actually update the data though rather than just replace the values for the purpose of a select query.
How about:
SELECT
i.ID,
i.DateValue,
D = CASE WHEN I.D <> 0 THEN I.D ELSE X.D END
FROM
Items I
OUTER APPLY (
SELECT TOP 1 S.D
FROM Items S
WHERE S.DATEVALUE < I.DATEVALUE AND S.D <> 0
ORDER BY S.DATEVALUE DESC
) X
SELECT t.id,
CASE WHEN t.D = 0 THEN t0.D
ELSE t.D END
FROM table AS t
LEFT JOIN table AS t0
ON t0.time =
(
SELECT MAX(time) FROM t0
WHERE t0.time < t.time
AND t0.D != 0
)
or if you want to avoid aggregates entirely,
SELECT t.id,
CASE WHEN t.D = 0 THEN t0.D
ELSE t.D END
FROM table AS t
LEFT JOIN table AS t0
ON t0.time < t.time
LEFT JOIN table AS tx
ON tx.time > t0.time
WHERE t0.D != 0
AND tx.D != 0
AND tx.id IS NULL -- i.e. there isn't any
I've a column that have 15 distinct values. I'd like to count how many there are of a few of them,
I've come up with e.g.
select a,COUNT(IFNULL(b != 1,NULL)),COUNT(IFNULL(b != 2,NULL)) from
mytable group by a
select a,SUM(CASE WHEN a = 1 THEN 1 ELSE 0)),SUM(CASE WHEN a = 2 THEN 1 ELSE 0)) from
mytable group by a
What's the best way of doing this ? (note, I need to pivot those values to columns,
a simple select a,b,count(*) from mytable where b=1 or b=2 group by a,b; won't do.)
Of the two methods suggested in the question, I recommend the second:
select a,
SUM(CASE WHEN b = 1 THEN 1 ELSE 0) b1,
SUM(CASE WHEN b = 2 THEN 1 ELSE 0) b2
from mytable
group by a
- as it is both simpler and (I think) easier to understand, and therefore to maintain. I recommend including column aliases, as they make the output easier to understand.
First of all you misunderstood the IFNULL function (you probably wanted IF). See the documentation http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html .
The second query you have in your question will give you what you want. But SUM(a=x) is more than sufficient. In MySQL true is equal to 1 and false is equal to 0.
have u try cross join?
select *
from (
select a, sum(...) as aSum
from mytable
where a...
group
by a
) as forA
cross join (
select b, sum(...) as bsum
from (
select *
from mytable
where b...
group
by b
)
) as forB;