How to modify temp table inside cursor? - sql-server

Question

I have temp table data in sql. I need modify data in that table.
Please find snapshot attached
I need to have a col having month data like for 01-03 jan-mar
this is code I have written. It's not working:
DECLARE #month VARCHAR(50) -- month
DECLARE #year VARCHAR(256) -- year
DECLARE #monthf VARCHAR(256) -- year
DECLARE #months VARCHAR(256) -- year
DECLARE db_cursor CURSOR FOR
SELECT months,[year] FROM #temp where len(months)>4
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #month,#year
WHILE ##FETCH_STATUS = 0
BEGIN
IF SUBSTRING(#month,0,3) = '01'
set #monthf='Jan'
ELSE IF SUBSTRING(#month,0,3) = '02'
set #monthf='Feb'
ELSE IF SUBSTRING(#month,0,3) = '03'
set #monthf='Mar'
ELSE IF SUBSTRING(#month,0,3) = '04'
set #monthf='Apr'
ELSE IF SUBSTRING(#month,0,3) = '05'
set #monthf='May'
ELSE IF SUBSTRING(#month,0,3) = '06'
set #monthf='Jun'
ELSE IF SUBSTRING(#month,0,3) = '07'
set #monthf='Jul'
ELSE IF SUBSTRING(#month,0,3) = '08'
set #monthf='Aug'
ELSE IF SUBSTRING(#month,0,3) = '09'
set #monthf='Sep'
ELSE IF SUBSTRING(#month,0,3) = '10'
set #monthf='Oct'
ELSE IF SUBSTRING(#month,0,3) = '11'
set #monthf='Nov'
ELSE IF SUBSTRING(#month,0,3) = '12'
set #monthf='Dec'
IF SUBSTRING(#month,4,2) = '01'
set #months='Jan'
ELSE IF SUBSTRING(#month,4,2) = '02'
set #months='Feb'
ELSE IF SUBSTRING(#month,4,2) = '03'
set #months='Mar'
ELSE IF SUBSTRING(#month,4,2) = '04'
set #months='Apr'
ELSE IF SUBSTRING(#month,4,2) = '05'
set #months='May'
ELSE IF SUBSTRING(#month,4,2) = '06'
set #months='Jun'
ELSE IF SUBSTRING(#month,4,2) = '07'
set #months='Jul'
ELSE IF SUBSTRING(#month,4,2) = '08'
set #months='Aug'
ELSE IF SUBSTRING(#month,4,2) = '09'
set #months='Sep'
ELSE IF SUBSTRING(#month,4,2) = '10'
set #months='Oct'
ELSE IF SUBSTRING(#month,4,2) = '11'
set #months='Nov'
ELSE IF SUBSTRING(#month,4,2) = '12'
set #months='Dec'
update #temp set [Month]= where months=
Delete from #temp where months=SUBSTRING(#month,0,3) and [Year]=#year
Delete from #temp where months=SUBSTRING(#month,4,2) and [Year]=#year
FETCH NEXT FROM db_cursor INTO #month,#year
END
CLOSE db_cursor
DEALLOCATE db_cursor
I need another column with month names like: for 01-03 it should give jan-mar
Can you please help me out? I need a separate column for month string data.

Answer 1

You don't need a cursor at all.
IF OBJECT_ID('tempdb..#Data') IS NOT NULL
DROP TABLE #Data
CREATE TABLE #Data (
Month VARCHAR(100),
ResultMonthText VARCHAR(100))
INSERT INTO #Data (
Month)
VALUES
('01-03'),
('07'),
('03'),
('03-05'),
('05-09'),
('02')
;WITH ParsedMonths AS
(
SELECT
D.Month,
D.ResultMonthText,
First = CONVERT(INT, SUBSTRING(D.Month, 1, 2)),
Second = CONVERT(INT, NULLIF(SUBSTRING(D.Month, 4, 2), ''))
FROM
#Data AS D
),
MonthNames AS
(
SELECT
D.Month,
D.ResultMonthText,
FirstAsName = SUBSTRING(
DATENAME(
MONTH,
DATEADD(MONTH, D.First, 0) - 1 ),
1,
3),
SecondAsName = SUBSTRING(
DATENAME(
MONTH,
DATEADD(MONTH, D.Second, 0) - 1 ),
1,
3)
FROM
ParsedMonths AS D
)
UPDATE D SET
ResultMonthText = D.FirstAsName + ISNULL('-' + D.SecondAsName, '')
FROM
MonthNames AS D
SELECT
*
FROM
#Data AS D
/*
Result:
Month ResultMonthText
------- ------------
01-03 Jan-Mar
07 Jul
03 Mar
03-05 Mar-May
05-09 May-Sep
02 Feb
*/
EDIT: Do this if you still want to keep your cursor (although I strongly suggest you stop using them whenever you can):
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #month,#year
WHILE ##FETCH_STATUS = 0
BEGIN
DECLARE #FirstMonthNumber INT = CONVERT(INT, SUBSTRING(#month, 1, 2))
DECLARE #SecondMonthNumber INT = CONVERT(INT, NULLIF(SUBSTRING(#month, 4, 2), ''))
DECLARE #FirstMonthText VARCHAR(10) = SUBSTRING(
DATENAME(
MONTH,
DATEADD(MONTH, #FirstMonthNumber, 0) - 1 ),
1,
3)
DECLARE #SecondMonthText VARCHAR(10) = SUBSTRING(
DATENAME(
MONTH,
DATEADD(MONTH, #SecondMonthNumber, 0) - 1 ),
1,
3)
update #temp set
YourNewMonthColumn = #FirstMonthText + ISNULL('-' + #SecondMonthText, '')
WHERE
months = #month
FETCH NEXT FROM db_cursor INTO #month,#year
END
I don't know why you update the column and then delete the row also.

Answer 2

Maybe
update #temp set [Month] = #monthf where months = #months