I have table that looks like this
Id Description
5 Null
4 This is a description
3 This is a description
2 Null
1 Null
I need to create an update statement that will update the null value if the previous value is not null.
Id Description
5 This is a description
4 This is a description
3 This is a description
2 Null
1 Null
Any advice or assistance would be much appreciated.
I think this is what you're looking for:
update toupdate
set description = updateto.description
from yourtable toupdate
join yourtable updateto on updateto.id = toupdate.id - 1
where updateto.description is not null
and toupdate.description is null;
SQL Fiddle Demo
This produces the following results:
ID DESCRIPTION
5 This is a description
4 This is a description
3 This is a description
2 (null)
1 (null)
EDIT: As pointed out by comment by Aaron Bertrand.
If your IDs aren't consecutive, you can use the row_number() function to join on instead of the ids:
with cte as (
select *, row_number() over (order by (select null)) rn
from yourtable
)
update toupdate
set description = updateto.description
from cte toupdate
join cte updateto on toupdate.rn = updateto.rn - 1
where updateto.description is not null
and toupdate.description is null;
You can change your order by criteria as needed.
Updated SQL Fiddle
The most common way (that I am aware of) to do this sort of thing is with a self-join:
-- WARNING: Untested Code
UPDATE YourTable
SET Origin.Description = Proxy.Description
FROM YourTable Origin
JOIN YourTable Proxy
ON Origin.Id = Proxy.Id - 1
WHERE Origin.Description IS NULL
AND Proxy.Description IS NOT NULL
This will join YourTable to itself so that one row looks like this:
Origin.Id | Origin.Description | Proxy.Id | Proxy.Description
------------------------------------------------------------------
5 | NULL | 4 | This is a description
EDIT
If you are not guaranteed always incrementing IDs then you will want to use ROW_NUMBER:
;WITH NumberedRows
AS
(
SELECT *
, ROW_NUMBER() OVER(ORDER BY Id) AS [Row #]
FROM YourTable
)
SELECT *
FROM NumberedRows Origin
JOIN NumberedRows Proxy
ON Origin.Id = Proxy.Id - 1
WHERE Origin.Description IS NULL
AND Proxy.Description IS NOT NULL
Related
(Select top 1 pvd.Code from PatientVisitDiags pvd
where pvd.PatientVisitId = pv.PatientVisitId
Order By pvd.Listorder) as "DX1",
(Select top 1 a.code from (Select top 2 pvd.Code,pvd.ListOrder from PatientVisitDiags pvd
where pvd.PatientVisitId = pv.PatientVisitId
Order By pvd.Listorder)a order by a.ListOrder DESC ) as "DX2",
(Select top 1 a.code from (Select top 3 pvd.Code,pvd.ListOrder from PatientVisitDiags pvd
where pvd.PatientVisitId = pv.PatientVisitId
Order By pvd.Listorder)a order by a.ListOrder DESC ) as "DX3",
(Select top 1 a.code from (Select top 4 pvd.Code,pvd.ListOrder from PatientVisitDiags pvd
where pvd.PatientVisitId = pv.PatientVisitId
Order By pvd.Listorder)a order by a.ListOrder DESC ) as "DX4",
(Select top 1 a.code from (Select top 5 pvd.Code,pvd.ListOrder from PatientVisitDiags pvd
where pvd.PatientVisitId = pv.PatientVisitId
Order By pvd.Listorder)a order by a.ListOrder DESC ) as "DX5"
The above code is what I am using currently (It is not optimal but is only being used once for a one time Data Export).
In the database that we are currently exporting from, there is a table PatientVisitDiags that has columns "ListOrder" and "Code". There can be between 1 and 5 codes. The ListOrder holds the number of that code. For example:
ListOrder|Code |
1 |M51.27 |
2 |M54.17 |
3 |G83.4 |
I am trying to export the Code to its corresponding Column in the new table(DX1,DX2..etc). If I sort by ListOrder I can get them in the order I need (Row 1 to DX1 | Row 2 to DX2 etc.) However when I run the above SQL code, If the source table only has 3 Codes DX4 and DX5 will repeat DX3. For Example:
DX1 |DX2 |DX3 |DX4 |DX5
M51.27 |M54.17 |G83.4 |G83.4 |G83.4
Is there a way to have TOP return NULL values if you Select TOP more than what is given? SQL Sever 2008 does not allow for OFFSET/FETCH, this is what I normally would have done given the option to select individual rows.
TL:DR
ID | Name
1 | Joe
2 | Eric
3 | Steve
4 | John
If I have a table like above and run
SELECT TOP 5 Name FROM Table
Is there anyway to return?
Joe
Eric
Steve
John
NULL
What you're really doing is pivoting. So pivot! Try this little query:
WITH Top5 AS (
SELECT TOP 5
Dx = 'DX' + Convert(varchar(11), Row_Number() OVER (ORDER BY pvd.Listorder)),
pvd.Code
FROM dbo.PatientVisitDiags pvd
WHERE pvd.PatientVisitId = #patientVisitId
)
SELECT *
FROM
Top5 t
PIVOT (Max(Code) FOR Dx IN (DX1, DX2, DX3, DX4, DX5)) p
;
To answer your second question about getting an unpivoted rowset, basically do the same thing but provide the 5 rows somehow and left join to the desired data.
WITH Data AS (
SELECT TOP 5
Seq = Row_Number() OVER(ORDER BY ID),
Name
FROM dbo.Table
ORDER BY ID
)
SELECT
n.Seq,
t.Name
FROM
(VALUES
(1), (2), (3), (4), (5) -- or a numbers-generating CTE perhaps
) n (Seq)
LEFT JOIN Top 5 t
ON n.Seq = t.Seq
;
Side note
The fact that you're doing this:
where pvd.PatientVisitId = pv.PatientVisitId
tells me you're not using ANSI joins. Stop. Don't do that any more. Put this join condition in the ON clause of a JOIN. It's the year 2016... why are you using join syntax from the last century?
Oh, and prefix the schema on the table names. Look it up--you'll find actual performance reasons why you should do that. It's not just about the time taken to find the correct schema, but also about the execution plan cache...
one at a time - answering the last question
create a table with a bunch of null
select top (5) col
from
(
select col from table1
union
select nulCol from nullTable
) tt
order by tt.col
Update duplicate column value with
Suppose I have a table with follow column
ID, Code, IsDuplicate, Description
I have n records inside and I would like to bulk update the IsDuplicate value if there is duplicate code inside.
Example
1 ABC null null
2 DEF null null
3 DEF null null
4 ABC null null
5 FGH null null
ID 1, 2, 3, 4 IsDuplicate will be updated to true.
How could it be done?
This will update all duplicate codes :
UPDATE T
SET ISDUPLICATE = 'TRUE'
FROM YOURTABLE T
WHERE EXISTS (SELECT 1
FROM (SELECT *
FROM (SELECT ROW_NUMBER()
OVER (
PARTITION BY CODE
ORDER BY ID)RN,
*
FROM YOURTABLE)A
WHERE RN > 1)B
WHERE B.CODE = T.CODE)
You should use group by in select query.
SELECT code, COUNT(*) c FROM table GROUP BY code HAVING c > 1;
Then you can update it based on your requirements.
I feel like I'm missing something really obvious here.
Using T-SQL/SQL-Server:
I have unique values in more than one column but want to select the max version based on one particular column.
Dataset:
Example
ID | Name| Version | Code
------------------------
1 | Car | 3 | NULL
1 | Car | 2 | 1000
1 | Car | 1 | 2000
Target status: I want my query to only select the row with the highest version value. Running a MAX on the version column pulls all three because of the distinct values in the 'Code' column:
SELECT ID
,Name
,MAX(Version)
,Code
FROM Table
GROUP BY ID, Name, Code
The net result is that I get all three entries as per the data set due to the unique values in the Code column, but I only want the top row (Version 3).
Any help would be appreciated.
You need to identify the row with the highest version as 1 query and use another outer query to pull out all the fields for that row. Like so:
SELECT t.ID, t.Name, GRP.Version, t.Code
FROM (
SELECT ID
,Name
,MAX(Version) as Version
FROM Table
GROUP BY ID, Name
) GRP
INNER JOIN Table t on GRP.ID = t.ID and GRP.Name = t.Name and GRP.Version = t.Version
You can also use row_number() to do this kind of logic, for example like this:
select ID, Name, Version, Code
from (
select *, row_number() over (order by Version desc) as RN
from Table1
) X where RN = 1
Example in SQL Fiddle
add the top statment to force the return of a single row. Also add the order by notation
SELECT top 1 ID
,Name
,MAX(Version)
,Code
FROM Table
GROUP BY ID, Name, Code
order by max(version) desc
I have a record table that is recording changes within a table. I can pull the data from the first table fine, however when i try to join in another table to add some of its column information it stops displaying the information.
PartNumber | PartDesc | value | date
1 | test | 1 | 3/4/2015
I wanted to include the Aisle tag's from the location table
PartNumber| AisleTag | AisleTagTwo
1 | A1 | N/A
here is what i have as my sql statement so far
Select t1.PartNumber, t1.PartDesc , t1.NewValue , t1.Date,t2.AisleTag,t2.AisleTagTwo
from InvRecord t1
JOIN PartAisleListTbl t2 ON t1.PartNumber = t2.PartNumber
where Date = (select max(Date) from InvRecord where t1.PartNumber = InvRecord.PartNumber)
order by t1.PartNumber
it is coming up blank, my original sql statement doesn't include anything from t2. I am not sure what approach to go with in terms of getting the data combined any help is much appreciated thank you !
this should be the end result
PartNumber | PartDesc | value | date | AisleTag | AisleTagTwo
1 | test | 1 | 3/4/2015 | A1 | N/A
Pull the most recent row (based on Date) for each PartNumber in Table A and append data from Table B (joined on PartNumber):
SELECT *
FROM (
SELECT A.PartNumber
, A.PartDesc
, A.NewValue
, A.Date
, B.AisleTag
, B.AisleTagTwo
, DateSeq = ROW_NUMBER() OVER(PARTITION BY A.PartNumber ORDER BY A.Date DESC)
FROM InvRecord A
LEFT JOIN PartAisleListTbl B
ON A.PartNumber = B.PartNumber
) A
WHERE A.DateSeq = 1
ORDER BY A.PartNumber
Are you returning no records at all, or only records with AisleTag and AisleTagTwo as null?
Your sentence "it is coming up blank, my original sql statement doesn't include anything from t2." makes it sound like you're getting records with nulls for the t2 fields.
If you are, then you probably have a record in t2 that has nulls for those fields.
For troubleshooting purposes, try running the query without the WHERE clause:
Select t1.PartNumber, t1.PartDesc , t1.NewValue , t1.Date,t2.AisleTag,t2.AisleTagTwo
from InvRecord t1
JOIN PartAisleListTbl t2 ON t1.PartNumber = t2.PartNumber
order by t1.PartNumber
If you do get records, your problem is with the WHERE clause. If you don't, your problem is with the PartNumber fields in InvRecord and PartAisleListTbl not matching.
Not sure why your's isn't working... is date in both t1 and t2 by any chance?
Here's it re factored to use a inline view instead of a correlated query wonder if it makes a difference.
Select t1.PartNumber, t1.PartDesc , t1.NewValue , t1.Date,t2.AisleTag,t2.AisleTagTwo
from InvRecord t1
JOIN PartAisleListTbl t2
ON t1.PartNumber = t2.PartNumber
JOIN (select max(Date) mdate, PartNumber from InvRecord GROUP BY PartNumber) t3
on t3.partNumber= T1.PartNumber
and T3.mdate = T1.Date
order by t1.PartNumber
I'm stuck with a query which should be pretty simple but, for reasons unknown, my brain is not playing ball here ...
Table:
id(int) | strategy (varchar) | value (whatever)
1 "ABC" whatevs
2 "ABC" yeah
3 "DEF" hello
4 "DEF" kitty
5 "QQQ" hurrr
The query should select ALL rows grouped on strategy but only one row per strategy - the one with the higest id.
In the case above, it should return rows with id 2, 4 and 5
SELECT id, strategy , value
FROM (
SELECT id, strategy , value
,ROW_NUMBER() OVER (PARTITION BY strategy ORDER BY ID DESC) rn
FROM Table_Name
) Sub
WHERE rn = 1
Working SQL FIDDLE
You can use window function to get the solution you want. Fiddle here
with cte as
(
select
rank()over(partition by strategy order by id desc) as rnk,
id, strategy, value from myT
)
select id, strategy, value from
cte where rnk = 1;
Try this:
SELECT T2.id,T1.strategy,T1.value
FROM TableName T1
INNER JOIN
(SELECT MAX(id) as id,strategy
FROM TableName
GROUP BY strategy) T2
ON T1.id=T2.id
Result:
ID STRATEGY VALUE
2 ABC yeah
4 DEF kitty
5 QQQ hurrr
See result in SQL Fiddle.
SELECT id, strategy , value
FROM (
SELECT id, strategy , value
,MAX(id) OVER (PARTITION BY strategy) MaxId
FROM YourTable
) Sub
WHERE id=MaxId
You may try this one as well:
SELECT id, strategy, value FROM TableName WHERE id IN (
SELECT MAX(id) FROM TableName GROUP BY strategy
)
Bit depends on your data, you might get results faster with it as it does not do sorting, but by the other hand it uses IN, which can slow you down if there is many 'strategies'