How can I avoid the infinite loop? - sql

Question

Getting an infinite loop. the cursor fetches one single record for testing purposes but it cannot leave the fetch loop. It is the first time I am using microsoft sql. I am not sure about the syntax and the positioning of the fetch statement.
I am trying to update invoice details , that is for one invoice there are more than one items. Please help.
Begin--1
Declare #Det_inv_cnt int, ---------count invoice in detail
#Cnt_item5 int, --------count item number 5
#Cnt_item6 int, --------count item number 6
#sprice money, --------sum vatable amt
#vat_amt money, --------vat amt
#inv int, --------invoice
#customer int, --------customer id
#sdate datetime, --------date
#edate datetime --------date
begin--2
Declare inv_id Cursor For (Select invoice from plat.dbo.iheader
Where customer in (Select id from plat.dbo.customer
Where custype = 1
and id = 2601)
and invoice = 2628
OPEN inv_id
FETCH NEXT FROM inv_id INTO #inv -----------------------------next invoice from cursor
WHILE ##FETCH_STATUS=0
BEGIN--------begin4
set #sprice = 0;
set #vat_amt = 0;
set #det_inv_cnt = 0;
set #cnt_item5 = 0;
set #cnt_item6 = 0;
set #customer = (select customer from plat.dbo.iheader where #inv = invoice);
set #Det_inv_cnt = (select count(1)
from plat.dbo.idetail d
where d.item in ('2','4')
and d.invoice = #inv)
If (#Det_inv_cnt>0) ---------------------------------------end if 10
Begin -----begin5 end if 10
--calculate vatable amt and vat round(0.15*sum(a.price),2)
set #sprice = (Select sum(price)
From plat.dbo.idetail
Where invoice = #inv
And item in ('2','4'));
set #vat_amt = (Select (0.15*(sum(price)))
From plat.dbo.idetail
Where invoice = #inv
And item in ('2','4'));
set #cnt_item5 = (Select count(1)
From plat.dbo.idetail
where item = '5'
and invoice = #inv
and customer = #customer);
set #sdate = (select sdate
From idetail
Where item ='2'
or item = '4'
And invoice = #inv);
set #edate = (select edate
From idetail
Where item ='2'
or item = '4'
And invoice = #inv);
--select details to insert new record
INSERT INTO idetail
( invoice
, item
, descriptio
, qty
, price
, date
, customer
, sdate
, edate
--,timestamp
,profileid
, id_item_code
, id_taxable_amt
, id_item_instock
, id_extended
, id_category_id
, id_subcategory_id
, id_rg_id
, id_svc_id
, id_sbd_id
, id_rate_id
, id_prorated )
values ( #inv --invoice
,'TAX#1003' --item
,'#VAT (Rs. '+ #sprice +' x 15%)' --descriptio
,1 --qty
,#vat_amt --price
,#sdate --date
,#customer --customer
,#sdate --sdate
,#edate --edate
--,CURRENT_TIMESTAMP
,-1 --profileid
,0 --itemcode
,#SPRICE --taxable amt
,null --id_item_instock, int,
,#VAT_AMT --id_extended, money,
,1002 --id_category_id, int,
,0 --id_subcategory_id, int,
,0 --id_rg_id, int,
,0 --id_svc_id, int,
,0 --id_sbd_id, int,
,0 --id_rate_id, int,
,null); --id_prorated, char(1)
/*From dbo.plat.idetail
Where item ='2'
or item = '4'
And invoice = #inv;
*/
Begin --11
If #Cnt_item5 > 0 ------------------------------------------------------if cnt_item 5 >0
Begin------6
--delete old VAT record
Delete from idetail
where invoice = #inv
and item = '5'
and customer = #customer;
--update roundoff item number 6
set #cnt_item6 = (Select count(1)
from plat.dbo.idetail w
where w.invoice = #inv
and w.customer = #customer
and w.item = '6')
If #Cnt_item6>0 -------------------------------------------if cnt_item6>0
Begin---7
update plat.dbo.idetail
set item = '5'
where invoice = #inv
and customer = #customer
and item = '6';
End;--7
Else -------------------------------------------------------------else cnt_item6
Begin--8
Insert into err_log(
El_customer,
El_Invoice,
El_msg,
El_date)
Values (
#customer,
#inv,
('Residential Script - Count of Item 6 returned 0'),
getdate());
End;--8
End; --end 6 of begin cnt5>0
End;--11
-- End;---5
---update header with vat_amt
Begin--9
Update plat.dbo.iheader
Set taxtotal = #vat_amt
where invoice = #inv
and customer = #customer;
end;--9
end;--5
Else ----------else 10 dev_inv_cnt
/* no item found the insert in table*/
begin--10
Insert into err_log(
El_customer,
El_Invoice,
El_msg,
El_date)
Values (
#customer
,#inv
,('Residential - Count of Item 2 and 4 returned 0')
,Getdate());
end;--10
--End; --------end begin 4 while
FETCH NEXT FROM inv_id INTO #inv --get nxt record for cursor invt id
End; ----begin 4
CLOSE inv_id;
DEALLOCATE inv_id;
--GO
end;---begin 2
End;--1

Answer 1

The FETCH NEXT FROM Inv_IdINTO #invnext instruction is within the ELSE branch of the former IF statement. It needs to be put after the ELSE branch

Answer 2

You're only fetching from the cursor once and your while loop is checking the status of that fetch. Since it presumably succeeded, that condition is always evaluated as true.
For what it's worth, here's the template that I use for my cursors:
declare cursorName cursor fast_forward local for
-- your select goes here
OPEN cursorName
WHILE (1=1)
BEGIN
FETCH NEXT FROM cursorName INTO --variable list here
if (##FETCH_STATUS <> 0)
BREAK;
-- do stuff here
END
CLOSE cursorName
DEALLOCATE cursorName