Tables have been created and used without and ID column, but ID column is now needed. (classic)
I heard everything could be done without cursors. I just need every row to contain a different int value so I was looking for some kind of row number function :
How do I use ROW_NUMBER()?
I can't tell exactly how to use it even with these exemples.
UPDATE [TableA]
SET [id] = (select ROW_NUMBER() over (order by id) from [TableA])
Subquery returned more than 1 value.
So... yes of course it return more than one value. Then how to mix both update and row number to get that column filled ?
PS. I don't need a precise order, just unique values. I also wonder if ROW_NUMBER() is appropriate in this situation...
You can use a CTE for the update
Example
Declare #TableA table (ID int,SomeCol varchar(50))
Insert Into #TableA values
(null,'Dog')
,(null,'Cat')
,(null,'Monkey')
;with cte as (
Select *
,RN = Row_Number() over(Order by (Select null))
From #TableA
)
Update cte set ID=RN
Select * from #TableA
Updated Table
ID SomeCol
1 Dog
2 Cat
3 Monkey
You can use a subquery too as
Declare #TableA table (ID int,SomeCol varchar(50))
Insert Into #TableA values
(null,'Dog')
,(null,'Cat')
,(null,'Monkey');
UPDATE T1
SET T1.ID = T2.RN
FROM #TableA T1 JOIN
(
SELECT ROW_NUMBER()OVER(ORDER BY (SELECT 1)) RN,
*
FROM #TableA
) T2
ON T1.SomeCol = T2.SomeCol;
Select * from #TableA
Related
I'm trying to get only a single row per Appointment Number in a table storing a history of appointments. It works fine with a few rows but then gets slower? Is this the best way to do this kind of check and I'm just missing some indexes or is there a better way?
DECLARE #temptable TABLE
(
id INT PRIMARY KEY NOT NULL
, ApptNumber INT NOT NULL
, ApptDate DATE NOT NULL
, Notes VARCHAR(50) NULL
)
INSERT INTO #temptable VALUES (1,1,'01-DEC-2018','First Appointment')
INSERT INTO #temptable VALUES (2,1,'01-DEC-2018','')
INSERT INTO #temptable VALUES (3,1,'01-DEC-2018','Rescheduled')
INSERT INTO #temptable VALUES (4,2,'02-DEC-2018','Second Appointment')
INSERT INTO #temptable VALUES (5,2,'02-DEC-2018','Cancelled')
INSERT INTO #temptable VALUES (6,3,'03-DEC-2018','Third Appointment')
INSERT INTO #temptable VALUES (7,4,'04-DEC-2018','Fourth Appointment')
SELECT * FROM #temptable
SELECT MAX(id) FROM #temptable GROUP BY ApptNumber
SELECT tt.* FROM #temptable tt
INNER JOIN (SELECT MAX(id) [Id] FROM #temptable GROUP BY ApptNumber) appts ON appts.Id = tt.id
Solution 1:
select * from (
SELECT f1.*, row_number() over(partition by ApptNumber order by id desc ) rang FROM #temptable f1
) tmp where rang=1
Solution 2:
with tmp as (
select ApptNumber, max(ID) MaxID
from #temptable
group by ApptNumber
)
select f1.* from #temptable f1 inner join tmp f2 on f1.ID=f2.MaxID
Solution 3:
select distinct f3.* from #temptable f1
cross apply
(
select top 1 * from #temptable f2
where f1.ApptNumber=f2.ApptNumber
order by f2.ID desc
) f3
Window function
SELECT tt.*
FROM (
SELECT *, row_number() over (partition by ApptNumber order by id desc) as rn
) tt
where tt.rn = 1
I have a table with these columns:
id (pk, int identity), imei (varchar), name (varchar), lastconnected (datetime)
Some of the entries in this table have the same name and imei, but different id and different lastconnected date.
How can I effectively filter out all entries that have duplicates (with a SQL script), and then delete the one with the latest lastconnected date?
A simple ROW_NUMBER and DELETE should do the trick:
WITH CTE AS
(
SELECT *,
RN = ROW_NUMBER() OVER(PARTITION BY imei, [name] ORDER BY lastconnected DESC)
FROM dbo.YourTable
)
DELETE FROM CTE
WHERE RN = 1;
This is easy and will solve your problem
DECLARE #table TABLE
(
id int,
name varchar(10),
imei varchar(10)
)
insert into #table select 1, 'a','a'
insert into #table select 2, 'b','a'
insert into #table select 3, 'c','a'
insert into #table select 4, 'a','a'
insert into #table select 5, 'c','a'
insert into #table select 6, 'a','a'
insert into #table select 7, 'c','a'
insert into #table select 8, 'a','a'
WHILE (exists (select '' from #table group by name , imei having count(*) > 1))
BEGIN
delete from #table where id in (
select max(id) from #table group by imei , name having count(*) > 1)
End
select * from #table
My first instinct is to use RANK(). This will delete all duplicates, not just the most recent, in cases where things are duplicated multiple times.
delete a
from (
select id, imei, name, lastconnected, RANK() over(partition by imei, name order by lastconnected) as [rank] from #temp
) as a
where a.rank>1
It selects the maximum of the date for each combination of name and iemi and then deletes that particular row.
DELETE FROM yourtablee
WHERE (lastconnecteddate,name,imei) in
(SELECT max(lastconnecteddate), name,imei
FROM yourtable
GROUP BY name,imei)
The first column of a table is the date.
I need to sort the rest of the data while actually updating the table according to date (descending). I can't use UPDATE and ORDER BY together.
I tried using something similar to this post:
UPDATE Test
SET Number = rowNumber
FROM Test
INNER JOIN
(SELECT ID, row_number() OVER (ORDER BY ID DESC) as rowNumber
FROM Test) drRowNumbers ON drRowNumbers.ID = Test.ID
in
SQL Server: UPDATE a table by using ORDER BY
But I cannot mix row_number and date.
Any help will be appreciated.
Use a CTE:
Check it here: http://rextester.com/NGTM78965
create table #t1 (id int, d datetime, rown int);
insert into #t1 values (1,'2016-05-01',0);
insert into #t1 values (2,'2016-05-04',0);
insert into #t1 values (3,'2016-06-01',0);
insert into #t1 values (4,'2016-04-03',0);
insert into #t1 values (5,'2016-05-12',0);
insert into #t1 values (6,'2016-08-01',0);
insert into #t1 values (7,'2016-05-15',0);
insert into #t1 values (8,'2016-05-25',0);
with cte (id, d, r) as
(
select id, d, row_number() over (order by d) r
from #t1
)
update #t1
set #t1.rown = cte.r
from cte inner join #t1 on #t1.id = cte.id;
select * from #t1 order by d
My data is set up as follows:
CREATE TABLE TableA
(
id int IDENTITY,
name varchar(256),
description varchar(256)
)
CREATE TABLE TableB
(
id int IDENTITY,
name varchar(256),
description varchar(256)
) --unique constraint on name, description
CREATE TABLE TableA_TableB
(
idA int,
idB int
) --composite key referencing TableA and TableB
The situation is that I have many duplicate records in TableB that violate the unique constraint, and those duplicate records are referenced in TableA_TableB. So I'm trying to remove those records, which is simple enough (using the following CTE), but what would be the best way to update the records in TableA_TableB to reflect this change, i.e, have the TableA_TableB records reference the same ID in TableB as opposed to different IDs for each of the duplicates?
;WITH cte
AS (SELECT ROW_NUMBER() OVER (PARTITION BY [Name], [Description]
ORDER BY ( SELECT 0)) RN
FROM TableB)
DELETE FROM cte
WHERE RN = 1
Note: changed b.RowNum=1 to b.RowNum>1
First, you should try with ROLLBACK and then, if it's OK, uncomment COMMIT (this script wasn't tested):
DECLARE #UpdatedRows TABLE(ID INT PRIMARY KEY);
BEGIN TRANSACTION;
;WITH Base
AS(
SELECT ROW_NUMBER() OVER (PARTITION BY [Name], [Description] ORDER BY ( SELECT 0)) RowNum,
MIN(id) OVER(PARTITION BY [Name], [Description]) AS NewID,
ID -- Old ID
FROM TableB
),TableB_RowsForUpdate
AS(
SELECT *
FROM Base b
WHERE b.RowNum>1
)
UPDATE target
SET IDB=b.NewID
OUTPUT deleted.IDB INTO #UpdatedRows
FROM TableA_TableB target
INNER JOIN TableB_RowsForUpdate b ON target.IDB=b.ID;
DELETE b
FROM TableB b INNER JOIN #UpdatedRows upd ON b.ID=upd.ID;
ROLLBACK;
-- COMMIT;
I have 2 temp Tables [Description] and [Institution], I want to have these two in one table.
They are both tables that look like this:
Table1; #T1
|Description|
blabla
blahblah
blagblag
Table2; #T2
|Institution|
Inst1
Inst2
Inst3
I want to get it like this:
Table3; #T3
|Description| |Institution|
blabla Inst1
blahblah Inst2
blagblag Inst3
They are already in sort order.
I just need to get them next to each other..
Last time I asked was something almost the same.
I used this query
Create Table #T3
(
[From] Datetime
,[To] Datetime
)
INSERT INTO #T3
SELECT #T1.[From]
, MIN(#T2.[To])
FROM #T1
JOIN #T2 ON #T1.[From] < #T2.[To]
GROUP BY #T1.[From]
Select * from #T3
It did work for the date values, but it won't work here ? :s
Thank you.
One thing that concerns me is that you say that the values "are already in sort order". There really is no default sort order -- if you don't specify a sort order, you are at the mercy of SQL Server to determine the order in which the data is returned. The solution below assumes that there is some way to sort the data such that the records "match up" (using the ORDER BY clauses).
Hope this helps,
John
-- Table 1 test data
Create Table #T1
(
[Description] nvarchar(30)
)
INSERT INTO #T1 ([Description]) VALUES ('desc1')
INSERT INTO #T1 ([Description]) VALUES ('desc2')
INSERT INTO #T1 ([Description]) VALUES ('desc3')
-- Table 2 test data
Create Table #T2
(
[Institution] nvarchar(30)
)
INSERT INTO #T2 (Institution) VALUES ('Inst1')
INSERT INTO #T2 (Institution) VALUES ('Inst2')
INSERT INTO #T2 (Institution) VALUES ('Inst3')
-- Create table 3
Create Table #T3
(
[Description] nvarchar(30),
[Institution] nvarchar(30)
);
-- Use CTE2 to add row numbers to the data; use the row numbers to join the tables
-- you must specify the sort order for the data in the tables
WITH CTE1 (Description, RowNum) AS
(
SELECT [Description], ROW_NUMBER() OVER(ORDER BY [Description]) as RowNum
FROM #T1
),
CTE2 (Institution, RowNum) AS
(
SELECT Institution, ROW_NUMBER() OVER(ORDER BY Institution) as RowNum
FROM #T2
)
INSERT INTO #T3
SELECT CTE1.Description, CTE2.Institution
FROM CTE1
LEFT JOIN CTE2 ON CTE1.RowNum = CTE2.RowNum
Select * from #T3