Sql cursor in infinite loop. What is wrong in this code? - sql

Hi I am trying to loop for each employee id in table.
BEGIN
declare #empId nvarchar(50)
declare cur Cursor LOCAL for
select EmpId from EmployeeMaster
open cur
fetch next from cur into #empId
while ##FETCH_STATUS =0
begin
select #empId
end
close cur
END
This is my query in stored procedure. What is wrong with this? it is giving me first employee id within infinite loop.
If i check while ##FETCH_STATUS =1 then no output given. just saying
Command(s) completed successfully.

You need to add fetch command after select
BEGIN
declare #empId nvarchar(50)
declare cur Cursor LOCAL for
select EmpId from EmployeeMaster
open cur
fetch next from cur into #empId
while ##FETCH_STATUS =0
begin
select #empId
fetch next from cur into #empId
end
close cur
END

Related

Delete multiple records from table through cursor in sql server

there are number of test IP's which I would like to remove through system defined sp
exec sp_delete_firewall_rule from sys.firewall_rules table in sql server
I am using below cursor but its not working
declare #name nvarchar(max)
declare cur CURSOR LOCAL for
select #name from sys.firewall_rules where [name] like '%TestIP%'
open cur
fetch next from cur into #name
while ##FETCH_STATUS = 0 BEGIN
exec sp_delete_firewall_rule #name
fetch next from cur into #name
END
close cur
deallocate cur
It worked for me, you just need to change a couple of things in your code.
In the select list include the table ColumnName [name] instead of variable. You did not pass any value to the variable so this gives a NULL result.
Include SP parameter while executing exec sp_delete_firewall_rule #name = #name1;
I have these IP’s in my firewall rules:
With the below code I am deleting the IP’s which has a name like TestIP1.
DECLARE #name1 nvarchar(128);
DECLARE MyCursor CURSOR FOR
SELECT [name] from sys.firewall_rules where [name] like '%TestIP1%';
OPEN MyCursor;
FETCH FROM MyCursor into #name1
WHILE ##FETCH_STATUS = 0 BEGIN
EXEC sp_delete_firewall_rule #name = #name1 ;
FETCH next from MyCursor into #name1
END
CLOSE MyCursor;
DEALLOCATE MyCursor;
GO
Now the result shows only 1 IP which is not included in the above delete list.

Dynamic Cursor from the procedure argument

I have a procedure that takes an argument. And I want to loop a cursor through the query based on that argument.
For example:
the argument is passed: salary
the cursor should be (select salary from emp) and loop through it.
How should I do that ?
DECLARE #ARGUMENT VARCHAR(50) = 'salary';
DECLARE #CURSOR_BODY VARCHAR(MAX) = '
declare #variable varchar(max)
declare cur cursor for
select '+ #argument + ' from emp
OPEN cur;
FETCH NEXT FROM cur INTO #variable
WHILE ##FETCH_STATUS=0
BEGIN
select #variable
FETCH NEXT FROM cur INTO #variable;
END
CLOSE cur
DEALLOCATE cur'
print #cursor_body
EXEC (#CURSOR_BODY)
Try sth. like this

How do I loop through the results of a SELECT statement sql and use the result for stored procedure?

I want to use the result of a select query into a stored procedure by using cursor but it doesn't work.
Here is my code:
DECLARE #NumberPhone varchar(50)
DECLARE CUR CURSOR STATIC FOR
SELECT MobilePhone
FROM info_client
OPEN CUR
FETCH NEXT FROM CUR INTO #NumberPhone
WHILE ##FETCH_STATUS = 0
BEGIN
DECLARE #return_value int, #idCli int, #sCode varchar(2)
EXEC #return_value = StoredP_Test
#sLignePhone = #NumberPhone,
#sIMEI ='00000000000000000',
#idCli = #idCli OUTPUT,
#sCode = #sCode OUTPUT
SELECT #idCli as N'#idCli',
#sCode as N'#sCode'
FETCH NEXT FROM CUR INTO #NumberPhone
SELECT 'Return Value' = #return_value
END
CLOSE CUR
DEALLOCATE CUR
This code duplicate the same result as the number of line of the select query.
Your code has an initial fetch of
FETCH NEXT FROM CUR INTO #NumberPhone
Your code has a fetch next inside the loop
FETCH NEXT FROM CUR INTO #sLigneAssValue
Didn't you want to fetch next into the #NumberPhone variable?
The #NumberPhone variable will never change.

Get Multiple Values in SQL Server Cursor

I have a cursor containing several columns from the row it brings back that I would like to process at once. I notice most of the examples I've seeing on how to use cursors show them assigning a particular column from the cursor to a scalar value one at a time, then moving to the next row,
e.g.
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #name
WHILE ##FETCH_STATUS = 0
BEGIN
--Do Stuff with #name scalar value, then get next row from cursor
FETCH NEXT FROM db_cursor INTO #name
END
What I want to know is if it's possible to do something like the following:
OPEN db_cursor
FETCH NEXT FROM db_cursor;
WHILE ##FETCH_STATUS = 0
BEGIN
SET #myName = db_cursor.name;
SET #myAge = db_cursor.age;
SET #myFavoriteColor = db_cursor.favoriteColor;
--Do stuff with scalar values
FETCH NEXT FROM db_cursor;
END
Help is always appreciated.
This should work:
DECLARE db_cursor CURSOR FOR SELECT name, age, color FROM table;
DECLARE #myName VARCHAR(256);
DECLARE #myAge INT;
DECLARE #myFavoriteColor VARCHAR(40);
OPEN db_cursor;
FETCH NEXT FROM db_cursor INTO #myName, #myAge, #myFavoriteColor;
WHILE ##FETCH_STATUS = 0
BEGIN
--Do stuff with scalar values
FETCH NEXT FROM db_cursor INTO #myName, #myAge, #myFavoriteColor;
END;
CLOSE db_cursor;
DEALLOCATE db_cursor;
Do not use ##fetch_status - this will return status from the last cursor in the current connection. Use the example below:
declare #sqCur cursor;
declare #data varchar(1000);
declare #i int = 0, #lastNum int, #rowNum int;
set #sqCur = cursor local static read_only for
select
row_number() over (order by(select null)) as RowNum
,Data -- you fields
from YourIntTable
open #cur
begin try
fetch last from #cur into #lastNum, #data
fetch absolute 1 from #cur into #rowNum, #data --start from the beginning and get first value
while #i < #lastNum
begin
set #i += 1
--Do your job here
print #data
fetch next from #cur into #rowNum, #data
end
end try
begin catch
close #cur --|
deallocate #cur --|-remove this 3 lines if you do not throw
;throw --|
end catch
close #cur
deallocate #cur

Cursor inside cursor

Main problem is about changing the index of rows to 1,2,3.. where contact-id and type is the same. but all columns can contain exactly the same data because of some ex-employee messed up and update all rows by contact-id and type. somehow there are rows that aren't messed but index rows are same. It is total chaos.
I tried to use an inner cursor with the variables coming from the outer cursor.
But It seems that its stuck in the inner cursor.
A part of the query looks like this:
Fetch NEXT FROM OUTER_CURSOR INTO #CONTACT_ID, #TYPE
While (##FETCH_STATUS <> -1)
BEGIN
IF (##FETCH_STATUS <> -2)
DECLARE INNER_CURSOR Cursor
FOR
SELECT * FROM CONTACTS
where CONTACT_ID = #CONTACT_ID
and TYPE = #TYPE
Open INNER_CURSOR
Fetch NEXT FROM INNER_CURSOR
While (##FETCH_STATUS <> -1)
BEGIN
IF (##FETCH_STATUS <> -2)
What can be the problem? Is ##FETCH_STATUS ambiguous or something?
EDIT: everything looks fine if i don't use this code inside inner cursor:
UPDATE CONTACTS
SET INDEX_NO = #COUNTER
where current of INNER_CURSOR
EDIT: here is the big picture:
BEGIN TRAN
DECLARE #CONTACT_ID VARCHAR(15)
DECLARE #TYPE VARCHAR(15)
DECLARE #INDEX_NO SMALLINT
DECLARE #COUNTER SMALLINT
DECLARE #FETCH_STATUS INT
DECLARE OUTER_CURSOR CURSOR
FOR
SELECT CONTACT_ID, TYPE, INDEX_NO FROM CONTACTS
WHERE
CONTACT_ID IN (SELECT CONTACT_ID FROM dbo.CONTACTS
WHERE CONTACT_ID IN(...)
GROUP BY CONTACT_ID, TYPE, INDEX_NO
HAVING COUNT(*) > 1
OPEN OUTER_CURSOR
FETCH NEXT FROM OUTER_CURSOR INTO #CONTACT_ID, #TYPE, #INDEX_NO
WHILE (##FETCH_STATUS <> -1)
BEGIN
IF (##FETCH_STATUS <> -2)
SET #COUNTER = 1
DECLARE INNER_CURSOR CURSOR
FOR
SELECT * FROM CONTACTS
WHERE CONTACT_ID = #CONTACT_ID
AND TYPE = #TYPE
FOR UPDATE
OPEN INNER_CURSOR
FETCH NEXT FROM INNER_CURSOR
WHILE (##FETCH_STATUS <> -1)
BEGIN
IF (##FETCH_STATUS <> -2)
UPDATE CONTACTS
SET INDEX_NO = #COUNTER
WHERE CURRENT OF INNER_CURSOR
SET #COUNTER = #COUNTER + 1
FETCH NEXT FROM INNER_CURSOR
END
CLOSE INNER_CURSOR
DEALLOCATE INNER_CURSOR
FETCH NEXT FROM OUTER_CURSOR INTO #CONTACT_ID, #TYPE, #INDEX_NO
END
CLOSE OUTER_CURSOR
DEALLOCATE OUTER_CURSOR
COMMIT TRAN
You have a variety of problems. First, why are you using your specific ##FETCH_STATUS values? It should just be ##FETCH_STATUS = 0.
Second, you are not selecting your inner Cursor into anything. And I cannot think of any circumstance where you would select all fields in this way - spell them out!
Here's a sample to go by. Folder has a primary key of "ClientID" that is also a foreign key for Attend. I'm just printing all of the Attend UIDs, broken down by Folder ClientID:
Declare #ClientID int;
Declare #UID int;
DECLARE Cur1 CURSOR FOR
SELECT ClientID From Folder;
OPEN Cur1
FETCH NEXT FROM Cur1 INTO #ClientID;
WHILE ##FETCH_STATUS = 0
BEGIN
PRINT 'Processing ClientID: ' + Cast(#ClientID as Varchar);
DECLARE Cur2 CURSOR FOR
SELECT UID FROM Attend Where ClientID=#ClientID;
OPEN Cur2;
FETCH NEXT FROM Cur2 INTO #UID;
WHILE ##FETCH_STATUS = 0
BEGIN
PRINT 'Found UID: ' + Cast(#UID as Varchar);
FETCH NEXT FROM Cur2 INTO #UID;
END;
CLOSE Cur2;
DEALLOCATE Cur2;
FETCH NEXT FROM Cur1 INTO #ClientID;
END;
PRINT 'DONE';
CLOSE Cur1;
DEALLOCATE Cur1;
Finally, are you SURE you want to be doing something like this in a stored procedure? It is very easy to abuse stored procedures and often reflects problems in characterizing your problem. The sample I gave, for example, could be far more easily accomplished using standard select calls.
You could also sidestep nested cursor issues, general cursor issues, and global variable issues by avoiding the cursors entirely.
declare #rowid int
declare #rowid2 int
declare #id int
declare #type varchar(10)
declare #rows int
declare #rows2 int
declare #outer table (rowid int identity(1,1), id int, type varchar(100))
declare #inner table (rowid int identity(1,1), clientid int, whatever int)
insert into #outer (id, type)
Select id, type from sometable
select #rows = count(1) from #outer
while (#rows > 0)
Begin
select top 1 #rowid = rowid, #id = id, #type = type
from #outer
insert into #innner (clientid, whatever )
select clientid whatever from contacts where contactid = #id
select #rows2 = count(1) from #inner
while (#rows2 > 0)
Begin
select top 1 /* stuff you want into some variables */
/* Other statements you want to execute */
delete from #inner where rowid = #rowid2
select #rows2 = count(1) from #inner
End
delete from #outer where rowid = #rowid
select #rows = count(1) from #outer
End
Do you do any more fetches? You should show those as well. You're only showing us half the code.
It should look like:
FETCH NEXT FROM #Outer INTO ...
WHILE ##FETCH_STATUS = 0
BEGIN
DECLARE #Inner...
OPEN #Inner
FETCH NEXT FROM #Inner INTO ...
WHILE ##FETCH_STATUS = 0
BEGIN
...
FETCH NEXT FROM #Inner INTO ...
END
CLOSE #Inner
DEALLOCATE #Inner
FETCH NEXT FROM #Outer INTO ...
END
CLOSE #Outer
DEALLOCATE #Outer
Also, make sure you do not name the cursors the same... and any code (check your triggers) that gets called does not use a cursor that is named the same. I've seen odd behavior from people using 'theCursor' in multiple layers of the stack.
This smells of something that should be done with a JOIN instead. Can you share the larger problem with us?
Hey, I should be able to get this down to a single statement, but I haven't had time to play with it further yet today and may not get to. In the mean-time, know that you should be able to edit the query for your inner cursor to create the row numbers as part of the query using the ROW_NUMBER() function. From there, you can fold the inner cursor into the outer by doing an INNER JOIN on it (you can join on a sub query). Finally, any SELECT statement can be converted to an UPDATE using this method:
UPDATE [YourTable/Alias]
SET [Column] = q.Value
FROM
(
... complicate select query here ...
) q
Where [YourTable/Alias] is a table or alias used in the select query.
I had the same problem,
what you have to do is declare the second cursor as:
DECLARE [second_cursor] Cursor LOCAL For
You see"CURSOR LOCAL FOR" instead of "CURSOR FOR"
I don't fully understand what was the problem with the "update current of cursor" but it is solved by using the fetch statement twice for the inner cursor:
FETCH NEXT FROM INNER_CURSOR
WHILE (##FETCH_STATUS <> -1)
BEGIN
UPDATE CONTACTS
SET INDEX_NO = #COUNTER
WHERE CURRENT OF INNER_CURSOR
SET #COUNTER = #COUNTER + 1
FETCH NEXT FROM INNER_CURSOR
FETCH NEXT FROM INNER_CURSOR
END