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##Rowcount is used to inform the number of rows affected for the last
select,insert,update or delete statements
declare #row int select 100 if ##rowcount>0 set #row=##rowcount ...
The above will return 0 because as soon as if ##rowcount>0 is executed
it is reset to 0 as it doesn't return any rows. So always assign to
variable first
Why does statement if ##rowcount>0 reset ##rowcount to 0? Isn't the value of ##rowcount affected only by select,insert,update and delete statements?
thank you
It is affected by the last statement. Like this SET statement
Declare #row int
select 100 union all select 200 union all select 300
set #row = ##rowcount;
SELECT #row, ##rowcount
If you read the actual Microsoft SQL Server Docs on MSDN, it gives examples of what statements affect ##ROWCOUNT. For example "such as" implies other statements like IF will also set it to zero
Statements such as USE, SET <option>, DEALLOCATE CURSOR, CLOSE CURSOR, BEGIN TRANSACTION or COMMIT TRANSACTION reset the ROWCOUNT value to 0.
Well,
I faced similar issue using sybase, which indicates that something might be wrong with "if".
declare #counter1 int
declare #counter2 int
select #counter1 = ##rowcount
if ##rowcount = 0 return
select #counter2 = ##rowcount
the output is:
counter1 = 3
counter2 = 0
I would expect 3(original one) or 1(because of Select).
This is even more strange because of
http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.infocenter.dc38151.1540/doc/html/san1278452893271.html
"The ##rowcount is not reset to zero by any statement which does not affect rows, such as an IF statement."
on other hand there is a lot of confusion how it really works(based on discussion in internet)
At the end in my solution in first line I assign ##rowcount to variable and my logic is based on that variable
Related
This seems like it should be pretty simple, but I cannot find a way to do it.
set nocount on;
Update MyTable
set MyField = 'value'
--where 1 = 1/0 -- comment in to test getting an error.
print convert(varchar, ##error)
print "blah blah" + convert(nvarchar, ##rowcount) -- this is always zero because of the previous statement
I tried storing them in a variable, but setting the variable generates a new ##rowcount and new ##error value.
I also tried using an if condition, because i don't care about the row count. But evaluating the if seems to also reset ##rowcount.
You can do it in a single statement, like this:
DECLARE #err INT, #cnt INT
SELECT #err=##ERROR, #cnt=##ROWCOUNT
I want to add a try catch to a while loop. The loop used while on ##ROWCOUNT > 0. In the while I have an update top (100) statement that works well without a try catch around it. When I add the try, the while ends in the first loop. What impact does the try have on ##ROWCOUNT that makes the while loop end even tough the update touched 100 records?
--do we have anything to process?
select top 1 * from SomeTable where processedFlag is null
WHILE(##ROWCOUNT > 0)
BEGIN
begin try
-- here I have an udpate top (100) statement that processes records with null flag in small batches
end try
begin catch
-- update ##ROWCOUNT so the while continues?
select top 1 * from SomeTable where processedFlag is null
end catch
END
I believe it because of
Statements such as USE, SET , DEALLOCATE CURSOR, CLOSE CURSOR,
BEGIN TRANSACTION or COMMIT TRANSACTION reset the ROWCOUNT value to 0.
May be END TRY is among them, but MSDN doesn't list all possible statements.
This will fix the problem:
DECLARE #i INT
SELECT #i = COUNT(*) FROM SomeTable WHERE processedFlag IS NULL
WHILE(#i > 0)
BEGIN
BEGIN TRY
UPDATE...
SET #i = ##ROWCOUNT
END TRY
BEGIN CATCH
SELECT #i = COUNT(*) FROM SomeTable WHERE processedFlag IS NULL
END CATCH
END
I have insert statements (simplified) in a SPROC like the following
SET ROWCOUNT 100
WHILE(1=1)
BEGIN
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
-- EDIT: Realized forgot to include this following vital line that is causing issue
SET #var = #var + ##ROWCOUNT
-- ##ROWCOUNT now takes on a value of 1, which will cause the following IF check to fail even when no lines are inserted
IF(##ROWCOUNT = 0)
BEGIN
BREAK
END
END
But the issue is, after any operation even when no more rows fit my some_condition, ##ROWCOUNT is equal to 1, not 0.
How can I break that loop when there are 0 rows returned matching my some_condition?
The "set" statement creates a row count of 1. What you should do is immediately save ##ROWCOUNT into a #rowCount variable and use that var later on.
declare #rowCount int
WHILE(1=1)
BEGIN
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
-- EDIT: Realized forgot to include this following vital line that is causing issue
SET #rowCount = ##ROWCOUNT
SET #var = #var + #rowCount
-- ##ROWCOUNT now takes on a value of 1, which will cause the following IF check to fail even when no lines are inserted
IF(#rowCount = 0)
BEGIN
BREAK
END
END
Also, you can simplify by setting #rowCount to -1 initially and changing the WHILE condition to #rowCount <> 0. The conditional BREAK will no longer be needed.
An alternative solution. This checks each iteration to see if the ID of the last inserted record has changed or not. If it hasn't changed, it indicates that no records were added that iteration.
SET ROWCOUNT 100
declare #id int;
WHILE(1=1)
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
IF(#id= ##identity)
BEGIN
BREAK
END
set #id = ##identity;
END
Try this solutions:
1st solution
Using ##ROWCOUNT in loop's condition.
SET ROWCOUNT 100
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
WHILE(##ROWCOUNT > 0)
BEGIN
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
END
2nd solition
Using goto.
SET ROWCOUNT 100
WHILE(1=1)
BEGIN
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
IF(##ROWCOUNT = 0)
BEGIN
goto label
END
END
label1:
print 'After lopp'
I think you should use select to get the ##rowcount into a variable. try this:
declare #number_of_rows int
SET ROWCOUNT 100
WHILE(1=1)
BEGIN
INSERT INTO table1
SELECT *
FROM table2
WHERE some_condition
SELECT #number_of_rows=##ROWCOUNT
IF (#number_of_rows = 0)
BEGIN
BREAK
END
END
Implemented solution similar to Moho, but used SELECT instead of SET to store ##ROWCOUNT.
I have a curious problem with an infinite loop in a TSQL cursor. The cursor loops infinitely when I do not add TOP 300 to the defining select statement of the cursor. The following is an example of the code: Any assistance to this issue is much appreciated.
DECLARE #Done BIT
SET #Done = 0
DECLARE cursOut CURSOR LOCAL FAST_FORWARD
FOR
SELECT
--TOP 300
FirstName FirstName
,LastName LastName
,MiddleName MiddleName
,Email Email
,Address1 Address1
,Address2 Address2
,City City
,[State] [State]
FROM StagedUsers
OPEN cursOut;
WHILE (#Done = 0)
BEGIN
--Fetch next row
FETCH NEXT
FROM cursOut
INTO ,#v_FirstName
,#v_LastName
,#v_MiddleName
,#v_Email
,#v_Address1
,#v_Address2
,#v_City
,#v_State
IF (##FETCH_STATUS <> 0)
BEGIN
SET #Done = 1
BREAK
END
--if #batch = 0
BEGIN TRANSACTION
--process statements
--updates or insert statements
--Commit transaction
COMMIT TRANSACTION
--End While
END
--CleanUp:
CLOSE cursOut
DEALLOCATE cursOut
Thanks,
Renegrin
First I think you do not need transaction here, I presume it is only one statement executed, so remove transaction from code.
Second do it without #done flag, it is confusing (it is probably not problem here).
DECLARE #v_FirstName VARCHAR(500),#v_LastName VARCHAR(500),#v_MiddleName VARCHAR(500),#v_Email VARCHAR(500),#v_Address1 VARCHAR(500),#v_Address2 VARCHAR(500),#v_City VARCHAR(500),#v_State VARCHAR(500)
DECLARE cursOut CURSOR FAST_FORWARD FOR
SELECT FirstName FirstName,LastName LastName,MiddleName MiddleName,Email Email,Address1 Address1,Address2 Address2,City City,[State] [State]
FROM StagedUsers
OPEN cursOut;
FETCH NEXT FROM cursOut INTO #v_FirstName,#v_LastName,#v_MiddleName,#v_Email,#v_Address1,#v_Address2,#v_City,#v_State
declare #i int = 1
WHILE ##FETCH_STATUS = 0
BEGIN
print cast(#i as varchar(10))
--> statement here
FETCH NEXT FROM cursOut INTO #v_FirstName,#v_LastName,#v_MiddleName,#v_Email,#v_Address1,#v_Address2,#v_City,#v_State
set #i = #i + 1
END
CLOSE cursOut
DEALLOCATE cursOut
Do you want to update current row where cursor point? If so, there is way to do it.
Is there any indexes on table? Can you post an update query?
In my stored procedure I have multiple similar variables #V1, #V2 ... #V20 (let's say 20 of them) FETCHED from a record. How would I use dynamic SQL to make 20 calls to another stored procedure using those variables as parameters?
Of course #V[i] syntax is incorrect, but it expresses the intent
fetch next from maincursor into #status, #V1, #V2, ...
while #i<21
begin
-- ??? execute sp_executesql 'SecondSP', '#myParam int', #myParam=#V[i]
-- or
-- ??? execute SecondSP #V[i]
set #i = #i+1
end
As others have said, set up a temporary table, insert the values that you need into it. Then "iterate" through it executing the necessary SQL from those values. This will allow you to have 0 to MANY values to be executed, so you don't have to set up a variable for each.
The following is a complete sample of how you may go about doing that without cursors.
SET NOCOUNT ON
DECLARE #dict TABLE (
id INT IDENTITY(1,1), -- a unique identity column for reference later
value VARCHAR(50), -- your parameter value to be passed into the procedure
executed BIT -- BIT to mark a record as being executed later
)
-- INSERT YOUR VALUES INTO #dict HERE
-- Set executed to 0 (so that the execution process will pick it up later)
-- This may be a SELECT statement into another table in your database to load the values into #dict
INSERT #dict
SELECT 'V1Value', 0 UNION ALL
SELECT 'V2Value', 0
DECLARE #currentid INT
DECLARE #currentvalue VARCHAR(50)
WHILE EXISTS(SELECT * FROM #dict WHERE executed = 0)
BEGIN
-- Get the next record to execute
SELECT
TOP 1 #currentid = id
FROM #dict
WHERE executed = 0
-- Get the parameter value
SELECT #currentvalue = value
FROM #dict
WHERE id = #currentid
-- EXECUTE THE SQL HERE
--sp_executesql 'SecondSP', '#myParam int', #myParam =
PRINT 'SecondSP ' + '#myParam int ' + '#myParam = ' + #currentvalue
-- Mark record as having been executed
UPDATE d
SET executed = 1
FROM #dict d
WHERE id = #currentid
END
Use a #TempTable
if you are at SQL Server 2005 you can create a #TempTable in the parent stored procedure, and it is available in the child stored procedure that it calls.
CREATE TABLE #TempTable
(col1 datatype
,col2 datatype
,col3 datatype
)
INSERT INTO #TempTable
(col1, col2, col3)
SELECT
col1, col2, col3
FROM ...
EXEC #ReturnCode=YourOtherProcedure
within the other procedure, you have access to #TempTable to select, delete, etc...
make that child procedure work on a set of data not on one element at a time
remember, in SQL, loops suck performance away!
Why not just use the table variable instead, and then just loop through the table getting each value.
Basically treat each row in a table as your array cell, with a table that has one column.
Just a thought. :)
This seems like an odd request - will you always have a fixed set of variables? What if the number changes from 20 to 21, and so on, are you constantly going to have to be declaring new variables?
Is it possible, instead of retrieving the values into separate variables, to return them each as individual rows and just loop through them in a cursor?
If not, and you have to use the individual variables as explained, here's one solution:
declare #V1 nvarchar(100)
set #V1 = 'hi'
declare #V2 nvarchar(100)
set #V2 = 'bye'
declare #V3 nvarchar(100)
set #V3 = 'test3'
declare #V4 nvarchar(100)
set #V4 = 'test4'
declare #V5 nvarchar(100)
set #V5 = 'end'
declare aCursor cursor for
select #V1
union select #V2 union select #V3
union select #V4 union select #V5
open aCursor
declare #V nvarchar(100)
fetch next from aCursor into #V
while ##FETCH_STATUS = 0
begin
exec TestParam #V
fetch next from aCursor into #V
end
close aCursor
deallocate aCursor
I don't really like this solution, it seems messy and unscalable. Also, as a side note - the way you phrased your question seems to be asking if there are arrays in T-SQL. By default there aren't, although a quick search on google can point you in the direction of workarounds for this if you absolutely need them.