I need to write a procedure that will allow me to select x amount of rows and at the same time update those rows so the calling application will know those records are locked and in use. I have a column in the table named "locked". The next time the procedure is called it will only pull the next x amount of records that do not have the "locked" column checked. I have read a little about the OUTPUT method for SQL server, but not sure that is what I want to do.
As you suggested, you can use the OUTPUT clause effectively:
Live demo: https://data.stackexchange.com/stackoverflow/query/8058/so3319842
UPDATE #tbl
SET locked = 1
OUTPUT INSERTED.*
WHERE id IN (
SELECT TOP 1 id
FROM #tbl
WHERE locked = 0
ORDER BY id
)
Also see this article:
http://www.sqlmag.com/article/tsql3/more-top-troubles-using-top-with-insert-update-and-delete.aspx
Vote for Cade Roux's answer, using OUTPUT:
UPDATE #tbl
SET locked = 1
OUTPUT INSERTED.*
WHERE id IN (SELECT TOP 1 id
FROM #tbl
WHERE locked = 0
ORDER BY id)
Previously:
This is one of the few times I can think of using a temp table:
ALTER PROCEDURE temp_table_test
AS
BEGIN
SELECT TOP 5000 *
INTO #temp_test
FROM your_table
WHERE locked != 1
ORDER BY ?
UPDATE your_table
SET locked = 1
WHERE id IN (SELECT id FROM #temp_test)
SELECT *
FROM #temp_test
IF EXISTS (SELECT NULL
FROM tempdb.dbo.sysobjects
WHERE ID = OBJECT_ID(N'tempdb..#temp_test'))
BEGIN
DROP TABLE #temp_test
END
END
This:
Fetches the rows you want, stuffs them into a local temp table
Uses the temp table to update the rows to be "locked"
SELECTs from the temp table to give you your resultset output
Drops the temp table because they live for the session
Related
I need to move what's been appended at the end of my table to its very beginning, however
the same record is being copied into destination.
In other words, between the ids 1 and 3567 I only have the record from the id 3567 repeated until the end. I believe that my outer and even inner sub-query lacks something ?
Thanks for the hint
Query:
UPDATE dbo.TABLE
SET Xwgs = dt.Xwgs, Ywgs = dt.Ywgs
FROM
(
SELECT
Xwgs,
Ywgs
FROM dbo.TABLE
WHERE
Id BETWEEN 3567 AND 7243
) dt
WHERE
Id BETWEEN 1 AND 3566
Is this what you want?
update t
set xwgs = dt.xwgs, ywgs = dt.ywgs
from mytable t
inner join (
select xwgs, ywgs
from mytable
where id between 3567 and 7243
) dt
on t.id = dt.id - 3566
The main difference with your query is that it properly correlates the target table and the derived table.
Note that this does not actually move the rows; all it does is copy the values from the upper bucket to the corresponding value in the lower bucket.
You know that You can always sort Your table with ORDER BY id DESC right?
Sometimes its needed do something strange. I do it like that:
Copy the whole table into a temp table (it may be #temporary table)
Drop or Truncate or Delete records from that table
Insert those records again from my temp table
Drop temp table
But an UPDATE is also a solution.
Tip: You can allow inserting values into identity (autoincreament) id column with SET IDENTITY_INSERT
SELECT *
INTO tmp__MyTable -- this will create a new table
FROM MyTable
ORDER BY id
DELETE FROM dbo.MyTable -- will throw an error on foreign keys conflicts
INSERT INTO MyTable (col,col2) -- column list here
SELECT col,col2
FROM tmp__MyTable
ORDER BY id DESC
-- or something like that:
-- ORDER BY CASE WHEN id <= 3566 THEN -id ELSE id END
-- DROP TABLE tmp__MyTable
i have a query that based on a condition updates a table with multiple rows.But every time i run the query it copies all the same data over again:
SET IDENTITY_INSERT table ON
INSERT INTO table(ID,NameID,tag)
SELECT
(SELECT MAX(ID) FROM table) + ROW_NUMBER()OVER (ORDER BY ID),
50000,
tag
FROM Table
WHERE NameID = 10000
SET IDENTITY_INSERT table OFF
so everytime the above query runs it copies the data with the nameID 10000 and puts it in a new rows with the nameID of 50000 and increments the ID.
so if this query runs the first time it will work fine the second time it runs it does the following
ID |NameId |tag
10 |100000 |4589
15 |100000 |7879
16 |500000 |4589 // first run of query gets the data which i wanted
17 |500000 |7879
18 |500000 |4589 // second run off query adds the same data over again
19 |500000 |7879
how can i tell it to check if 50000 exists in the table dont do an insert?
I have no idea why you are turning identity insert off. That seems to defeat the purpose of an identity column. But, that is not central to your question.
You can use not exists:
INSERT INTO table (ID, NameID, tag)
SELECT (SELECT MAX(ID) FROM table) + ROW_NUMBER()OVER (ORDER BY ID),
50000, tag
FROM Table t
WHERE NameID = 10000 AND
NOT EXISTS (SELECT 1 FROM table t2 WHERE t2.NameId = t50000 AND t2.tag = t.tag);
I belive you can use "if not exists" this case
if not exists("condition") begin
"insert"
end
I am trying to get the row number of an inserted record so I can use it for a select statement. What I am trying to accomplish is insert a person into one table, get that row number and then select something from another table where the row numbers match. Here is what I got so far:
INSERT INTO TableA Values (‘Person’)
Select timeToken
From
(
Select
Row_Number() Over (Order By tokenOrder) As RowNum
, *
From TableB WHERE taken = false
) t2
Where RowNum = (Row Number of Inserted Item)
How do I get the row number of the inserted item, I want to compare ids as some records might have been deleted so they would not match.
TABLEA Data (primary key is id)
id name
3 John
12 Steve
TABLEB Data (primary key is id)
id timeToken tokenOrder taken
2 1:00am 1 false
3 2:00am 2 false
5 3:00am 3 true
6 4:00am 4 false
My expect result when I insert person, the select take would return 4:00am
I am doing this in a stored procedure.
It is an error to think that rows have numbers unless an ORDER BY clause is included.
The only way to find a row after you have inserted it is to search for it. Presumably your table has a primary key; use that to search for it.
Try This .It may help you out
Declare #TableA_PK BIGINT
INSERT INTO TableA Values ('Person')
SET #TableA_PK=SCOPE_IDENTITY()
Select timeToken
From
(
Select
Row_Number() Over (Order By tokenOrder) As RowNum
, *
From TableB WHERE taken = false
) t2
Where RowNum =#TableA_PK
SCOPE_IDENTITY(): Scope Identity will captures the last inserted record primary key value and which can be stored in a varaible and
and then it can be for further re-use
By the sounds of it you are trying to do something like what is listed on thhe following link LINK - SQL Server - Return value after INSERT
Basically :
INSERT INTO TableA (Person)
OUTPUT Inserted.ID
VALUES('bob');
Adding a foreign key constraint(referencing primary key in table A) in table b will be good since you won't be able to delete records from table A without deleting them from table B. It'll be helpful for comparing the records using ID.
Try this
declare #rowNum int;
INSERT INTO TableA Values ('Person')
SET #rowNum =SCOPE_IDENTITY()
select * from TableA where id = #rowNum
I am using ms-sql server. I have table which I want to update from select statement. For example the table which I want to update is Table_A with 2 rows in it. The update statement from which I want to update Table_A return 10 rows. So I want to update Table_A 10 times. The problem is that Table_A is updated 2 times(the count of rows in Table_A).
Example:
CREATE TABLE #tmp
(
AccountID INT,
Inflow DECIMAL(10,2)
)
DECLARE #n INT = 0
WHILE (#n <10 )
BEGIN
INSERT INTO #tmp SELECT 2, 10
SET #n += 1
END
UPDATE dbo.Table_A
SET Balance += sss.Inflow
FROM ( SELECT t.AccountID ,
t.Inflow
FROM #tmp AS t
) AS sss
WHERE dbo.tAccount.AccountID = sss.AccountID;
-- Updates only 2 times
-- What I expected here is Table_A to be updated as many times as the count of the select statement which is 10, based on the insert before.
Your expectation is wrong. Admittedly, the documentation buries this idea:
The example runs without error, but each SalesYTD value is updated
with only one sale, regardless of how many sales actually occurred on
that day. This is because a single UPDATE statement never updates the
same row two times.
The documentation continues with the solution:
In the situation in which more than one sale for a specified
salesperson can occur on the same day, all the sales for each sales
person must be aggregated together within the UPDATE statement, as
shown in the following example:
So, simply aggregate before doing the join:
UPDATE dbo.Table_A
SET Balance += sss.Inflow
FROM (SELECT t.AccountID, SUM(t.Inflow) as Inflow
FROM #tmp t
GROUP BY t.AccountId
) sss
WHERE dbo.tAccount.AccountID = sss.AccountID;
Note you can also write this as:
UPDATE a
SET Balance += sss.Inflow
FROM dbo.Table_A a JOIN
(SELECT t.AccountID, SUM(t.Inflow) as Inflow
FROM #tmp t
GROUP BY t.AccountId
) sss
ON a.AccountID = sss.AccountID;
This makes the JOIN more explicit.
I'm trying to select the top 1 record with recordStatus=0 and at the same time update the recordStatus column to 1 in a stored procedure, My question is Can it be done in one select statement or do I have to use 3 statements?, here's what I got:
PROCEDURE sp_getRecord
#recordID varchar(30) = NULL
AS
BEGIN
SELECT TOP (1) #recordID = recordID
FROM TABLEA
WHERE recordStatus = 0
UPDATE TABLEA
SET recordStatus = 1
WHERE recordID = #recordID
SELECT *
FROM TABLEA
WHERE recordID = #recordID
END
I have tried doing a research, triggers and no luck, hope some one can help. I'm not very proficient at SQL.
Thank you.
Yes it can and should be done in one statement.
You are currently looking up the same row three times. As well as being inefficient this can also cause concurrency problems.
Assuming that you are using the table as a queue there is nothing in your present code that stops two concurrent transactions both running the SELECT and receiving the same #recordID.
Your current code does not have an ORDER BY. That means it is arbitrary which will be updated. If you simply don't care (a heap queue) then you can use.
UPDATE TOP(1) TABLEA
SET recordStatus = 1
OUTPUT inserted.*
WHERE recordStatus = 0
If you do, in fact, require an ORDER BY then you can use a CTE
WITH T AS
(
SELECT TOP (1) recordID
FROM TABLEA
WHERE recordStatus = 0
ORDER BY recordID
)
UPDATE T
SET recordStatus = 1
OUTPUT INSERTED.*
update top (1) TABLEA set recordStatus = 1 where recordStatus = 0