SQL : Turning rows into columns - sql

I need to turning the value of a row into column - for example:
SELECT s.section_name,
s.section_value
FROM tbl_sections s
this outputs :
section_name section_value
-----------------------------
sectionI One
sectionII Two
sectionIII Three
desired output :
sectionI sectionII sectionIII
-----------------------------------------
One Two Three

This is probably better done client-side in the programming language of your choice.
You absolutely need to know the section names in advance to turn them into column names.
Updated answer for Oracle 11g (using the new PIVOT operator):
SELECT * FROM
(SELECT section_name, section_value FROM tbl_sections)
PIVOT
MAX(section_value)
FOR (section_name) IN ('sectionI', 'sectionII', 'sectionIII')
For older versions, you could do some self-joins:
WITH
SELECT section_name, section_value FROM tbl_sections
AS
data
SELECT
one.section_value 'sectionI',
two.section_value 'sectionII',
three.section_value 'sectionIII'
FROM
select selection_value from data where section_name = 'sectionI' one
CROSS JOIN
select selection_value from data where section_name = 'sectionII' two
CROSS JOIN
select selection_value from data where section_name = 'sectionIII' three
or also use the MAX trick and "aggregate":
SELECT
MAX(DECODE(section_name, 'sectionI', section_value, '')) 'sectionI',
MAX(DECODE(section_name, 'sectionII', section_value, '')) 'sectionII',
MAX(DECODE(section_name, 'sectionIII', section_value, '')) 'sectionIII'
FROM tbl_sections

Related

Can I use string_split with enforcing combination of labels?

So I have the following table:
Id Name Label
---------------------------------------
1 FirstTicket bike|motorbike
2 SecondTicket bike
3 ThirdTicket e-bike|motorbike
4 FourthTicket car|truck
I want to use string_split function to identify rows that have both bike and motorbike labels.
So the desired output in my example will be just the first row:
Id Name Label
--------------------------------------
1 FirstTicket bike|motorbike
Currently, I am using the following query but it is returning row 1,2 and 3. I only want the first. Is it possible?
SELECT Id, Name, Label FROM tickets
WHERE EXISTS (
SELECT * FROM STRING_SPLIT(Label, '|')
WHERE value IN ('bike', 'motorbike')
)
You can use APPLY & do aggregation :
SELECT t.id, t.FirstTicket, t.Label
FROM tickets t CROSS APPLY
STRING_SPLIT(t.Label, '|') t1
WHERE t1.value IN ('bike', 'motorbike')
GROUP BY t.id, t.FirstTicket, t.Label
HAVING COUNT(DISTINCT t1.value) = 2;
However, this breaks the normalization rules you should have separate table tickets.
You could just use string functions for this:
select t.*
from mytable t
where
'|' + label + '|' like '%|bike|%'
and '|' + label + '|' like '%|motorbike|%'
I would expect this to be more efficient than other methods that split and aggregate.
Please note, however, that you should really consider fixing your data model. Instead of storing delimited lists, you should have a separated table to represent the relation between tickets and labels, with one row per ticket/label tuple. Storing delimited lists in database column is a well-know SQL antipattern, that should be avoided at all cost (hard to maintain, hard to query, hard to enforce data integrity, inefficicent, ...). You can have a look at this famous SO post for more on this topic.
Yogesh beat me to it; my solution is similar but with a HUGE performance improvement worth pointing out. We'll start with this sample data:
SET NOCOUNT ON;
IF OBJECT_ID('tempdb..#tickets','U') IS NOT NULL DROP TABLE #tickets;
CREATE TABLE #tickets (Id INT, [Name] VARCHAR(50), Label VARCHAR(1000));
INSERT #tickets (Id, [Name], Label)
VALUES
(1,'FirstTicket' , 'bike|motorbike'),
(2,'SecondTicket', 'bike'),
(3,'ThirdTicket' , 'e-bike|motorbike'),
(4,'FourthTicket', 'car|truck'),
(5,'FifthTicket', 'motorbike|bike');
Now the original and much improved version:
-- Original
SELECT t.id, t.[Name], t.Label
FROM #tickets AS t
CROSS APPLY STRING_SPLIT(t.Label, '|') t1
WHERE t1.[value] IN ('bike', 'motorbike')
GROUP BY t.id, t.[Name], t.Label
HAVING COUNT(DISTINCT t1.[value]) = 2;
-- Improved Version Leveraging APPLY to avoid a sort
SELECT t.Id, t.[Name], t.Label
FROM #tickets AS t
CROSS APPLY
(
SELECT 1
FROM STRING_SPLIT(t.Label,'|') AS split
WHERE split.[value] IN ('bike','motorbike')
HAVING COUNT(*) = 2
) AS isMatch(TF);
Now the execution plans:
If you compare the costs: the "sortless" version is query 4.36 times faster than the original. In reality it's more because, with the first version, we're not just sorting, we are sorting three columns - an int and two (n)varchars. Because sorting costs are N * LOG(N), the original query gets exponentially slower the more rows you throw at it.

How to use unpivot operator to combine rows and columns?

I need to group customers by GroupName. Customers can be duplicated on each GroupName. Each GroupName has a unique number called "GroupCode" in table OCQG. Customer table (OCRD) has separate column for Each GroupCode. As an example, C-0001 customer can have more group names.We can identify GroupCodes for each customer by see Group1,...,Group64 column values.(If this value = Y).Table structure as follows.Please help me.
I tried following query.But it didn't work.
SELECT p.CardCode, REPLACE(p.QryGroup,'GROUP','') groupcode, ocqg.GroupName
FROM ocrd UNPIVOT
( value
FOR groupcode IN ([QryGroup1],[QryGroup2],[QryGroup3])
) as p,
ocqg
WHERE value = 'Y' and
ocqg.GroupCode = REPLACE(p.groupcode,'GROUP','')
order by p.CardCode
Table Structure as follows,
I recommend using APPLY for this purpose:
SELECT ocrd.CardCode, v.groupcode, ocqg.GroupName
FROM ocrd CROSS APPLY
(VALUES (1, QryGroup1),
(2, QryGroup2),
(3, QryGroup3),
. . .
) v(GroupCode, Value) JOIN
ocqg
ON ocqg.GroupCode = v.GroupCode
WHERE v.value = 'Y'
ORDER BY p.CardCode;
UNPIVOT is bespoke syntax for SQL Server and Oracle that does one thing.
On the other hand, APPLY implements "lateral join"s.' These are very powerful -- much more powerful than UNPIVOT -- and supported by more databases.

Modify my SQL Server query -- returns too many rows sometimes

I need to update the following query so that it only returns one child record (remittance) per parent (claim).
Table Remit_To_Activate contains exactly one date/timestamp per claim, which is what I wanted.
But when I join the full Remittance table to it, since some claims have multiple remittances with the same date/timestamps, the outermost query returns more than 1 row per claim for those claim IDs.
SELECT * FROM REMITTANCE
WHERE BILLED_AMOUNT>0 AND ACTIVE=0
AND REMITTANCE_UUID IN (
SELECT REMITTANCE_UUID FROM Claims_Group2 G2
INNER JOIN Remit_To_Activate t ON (
(t.ClaimID = G2.CLAIM_ID) AND
(t.DATE_OF_LATEST_REGULAR_REMIT = G2.CREATE_DATETIME)
)
where ACTIVE=0 and BILLED_AMOUNT>0
)
I believe the problem would be resolved if I included REMITTANCE_UUID as a column in Remit_To_Activate. That's the REAL issue. This is how I created the Remit_To_Activate table (trying to get the most recent remittance for a claim):
SELECT MAX(create_datetime) as DATE_OF_LATEST_REMIT,
MAX(claim_id) AS ClaimID,
INTO Latest_Remit_To_Activate
FROM Claims_Group2
WHERE BILLED_AMOUNT>0
GROUP BY Claim_ID
ORDER BY Claim_ID
Claims_Group2 contains these fields:
REMITTANCE_UUID,
CLAIM_ID,
BILLED_AMOUNT,
CREATE_DATETIME
Here are the 2 rows that are currently giving me the problem--they're both remitts for the SAME CLAIM, with the SAME TIMESTAMP. I only want one of them in the Remits_To_Activate table, so only ONE remittance will be "activated" per Claim:
enter image description here
You can change your query like this:
SELECT
p.*, latest_remit.DATE_OF_LATEST_REMIT
FROM
Remittance AS p inner join
(SELECT MAX(create_datetime) as DATE_OF_LATEST_REMIT,
claim_id,
FROM Claims_Group2
WHERE BILLED_AMOUNT>0
GROUP BY Claim_ID
ORDER BY Claim_ID) as latest_remit
on latest_remit.claim_id = p.claim_id;
This will give you only one row. Untested (so please run and make changes).
Without having more information on the structure of your database -- especially the structure of Claims_Group2 and REMITTANCE, and the relationship between them, it's not really possible to advise you on how to introduce a remittance UUID into DATE_OF_LATEST_REMIT.
Since you are using SQL Server, however, it is possible to use a window function to introduce a synthetic means to choose among remittances having the same timestamp. For example, it looks like you could approach the problem something like this:
select *
from (
select
r.*,
row_number() over (partition by cg2.claim_id order by cg2.create_datetime desc) as rn
from
remittance r
join claims_group2 cg2
on r.remittance_uuid = cg2.remittance_uuid
where
r.active = 0
and r.billed_amount > 0
and cg2.active = 0
and cg2.billed_amount > 0
) t
where t.rn = 1
Note that that that does not depend on your DATE_OF_LATEST_REMIT table at all, it having been subsumed into the inline view. Note also that this will introduce one extra column into your results, though you could avoid that by enumerating the columns of table remittance in the outer select clause.
It also seems odd to be filtering on two sets of active and billed_amount columns, but that appears to follow from what you were doing in your original queries. In that vein, I urge you to check the results carefully, as lifting the filter conditions on cg2 columns up to the level of the join to remittance yields a result that may return rows that the original query did not (but never more than one per claim_id).
A co-worker offered me this elegant demonstration of a solution. I'd never used "over" or "partition" before. Works great! Thank you John and Gaurasvsa for your input.
if OBJECT_ID('tempdb..#t') is not null
drop table #t
select *, ROW_NUMBER() over (partition by CLAIM_ID order by CLAIM_ID) as ROW_NUM
into #t
from
(
select '2018-08-15 13:07:50.933' as CREATE_DATE, 1 as CLAIM_ID, NEWID() as
REMIT_UUID
union select '2018-08-15 13:07:50.933', 1, NEWID()
union select '2017-12-31 10:00:00.000', 2, NEWID()
) x
select *
from #t
order by CLAIM_ID, ROW_NUM
select CREATE_DATE, MAX(CLAIM_ID), MAX(REMIT_UUID)
from #t
where ROW_NUM = 1
group by CREATE_DATE

Order by data as per supplied Id in sql

Query:
SELECT *
FROM [MemberBackup].[dbo].[OriginalBackup]
where ration_card_id in
(
1247881,174772,
808454,2326154
)
Right now the data is ordered by the auto id or whatever clause I'm passing in order by.
But I want the data to come in sequential format as per id's I have passed
Expected Output:
All Data for 1247881
All Data for 174772
All Data for 808454
All Data for 2326154
Note:
Number of Id's to be passed will 300 000
One option would be to create a CTE containing the ration_card_id values and the orders which you are imposing, and the join to this table:
WITH cte AS (
SELECT 1247881 AS ration_card_id, 1 AS position
UNION ALL
SELECT 174772, 2
UNION ALL
SELECT 808454, 3
UNION ALL
SELECT 2326154, 4
)
SELECT t1.*
FROM [MemberBackup].[dbo].[OriginalBackup] t1
INNER JOIN cte t2
ON t1.ration_card_id = t2.ration_card_id
ORDER BY t2.position DESC
Edit:
If you have many IDs, then neither the answer above nor the answer given using a CASE expression will suffice. In this case, your best bet would be to load the list of IDs into a table, containing an auto increment ID column. Then, each number would be labelled with a position as its record is being loaded into your database. After this, you can join as I have done above.
If the desired order does not reflect a sequential ordering of some preexisting data, you will have to specify the ordering yourself. One way to do this is with a case statement:
SELECT *
FROM [MemberBackup].[dbo].[OriginalBackup]
where ration_card_id in
(
1247881,174772,
808454,2326154
)
ORDER BY CASE ration_card_id
WHEN 1247881 THEN 0
WHEN 174772 THEN 1
WHEN 808454 THEN 2
WHEN 2326154 THEN 3
END
Stating the obvious but note that this ordering most likely is not represented by any indexes, and will therefore not be indexed.
Insert your ration_card_id's in #temp table with one identity column.
Re-write your sql query as:
SELECT a.*
FROM [MemberBackup].[dbo].[OriginalBackup] a
JOIN #temps b
on a.ration_card_id = b.ration_card_id
order by b.id

differentiate rows in a union table

I m selecting data from two different tables with no matching columns using this sql query
select * from (SELECT s.shout_id, s.user_id, s.time FROM shouts s
union all
select v.post_id, v.sender_user_id, v.time from void_post v)
as derived_table order by time desc;
Now is there any other way or with this sql statement only can i
differentiate the data from the two tables.
I was thinking of a dummy row that can be created at run-time(in the select statement only ) which would flag the row from the either tables.
As there is no way i can differentiate the shout_id that is thrown in the unioned table is
shout_id from the shout table or from the void_post table.
Thanks
Pradyut
You can just include an extra column in each select (I'd suggest a BIT)
select * from
(SELECT s.shout_id, s.user_id, s.time, 1 AS FromShouts FROM shouts s
union all
select v.post_id, v.sender_user_id, v.time, 0 AS FromShouts from void_post v)
as derived_table order by time desc;
Sure, just add a new field in your select statement called something like source with a different constant value for each source.
SELECT s.shout_id, s.user_id, s.time, 'shouts' as source FROM shouts s
UNION ALL
SELECT v.post_id, v.sender_user_id, v.time, 'void_post' as source FROM void_post v
A dummy variable is a nice way to do it. There isn't much overhead in the grand scheme of things.
p.s., the dummy variable represents a column and not a row.