MS SQL Store procedure insert not work - sql

Question

I tried creating a store procedure for MS SQL
CREATE PROCEDURE YEARENDPROCESSING
AS
DECLARE #VAR AS VARCHAR(9)
DECLARE ACURSOR CURSOR FOR
SELECT COLUMN FROM TABLEA
OPEN ACURSOR
FETCH NEXT FROM ACURSOR INTO #VAR
while ##FETCH_STATUS = 0
BEGIN
INSERT INTO TABLEB SELECT * FROM TABLEC WHERE TABLEC.COLUMNC = #VAR
FETCH NEXT FROM ACURSOR INTO #VAR
END
CLOSE ACURSOR
DEALLOCATE ACURSOR
Assuming TableC column and TableB have identical columns
I get the result saying X rows affected
But in actual table I see nothing.
I have a new Finding
CREATE PROCEDURE YEARENDPROCESSING
AS
DECLARE #VAR AS VARCHAR(9)
DECLARE ACURSOR CURSOR FOR
SELECT COLUMN FROM TABLEA
OPEN ACURSOR
FETCH NEXT FROM ACURSOR INTO #VAR
while ##FETCH_STATUS = 0
BEGIN
INSERT INTO TABLEB SELECT * FROM TABLEC WHERE TABLEC.COLUMNC = #VAR
DELETE TABLEF where columnf = #VAR
FETCH NEXT FROM ACURSOR INTO #VAR
END
CLOSE ACURSOR
DEALLOCATE ACURSOR
Will get x row affected for the insert and x row affected for the delete
But the actual fact is insert result cannot be seen in the physical table itself. I can see the result of I remove the Delete query. Anyone knows why?

Answer 1

Your code shouldn't have a cursor. You can do this:
CREATE PROCEDURE dbo.YearEndProcessing
AS
BEGIN
SET NOCOUNT ON;
INSERT dbo.TableB(column1, column2, ...)
SELECT column1, column2, ...
FROM dbo.TableA;
END
GO
Well, you changed the code, now there's a third table involved, so let me try again without a cursor:
CREATE PROCEDURE dbo.YearEndProcessing
AS
BEGIN
SET NOCOUNT ON;
INSERT dbo.TableB(column1, column2, ...)
SELECT c.column1, c.column2, ...
FROM dbo.TableA AS a
INNER JOIN dbo.TableC AS c
ON a.[Column] = c.[ColumnC];
END
GO
Or:
CREATE PROCEDURE dbo.YearEndProcessing
AS
BEGIN
SET NOCOUNT ON;
INSERT dbo.TableB(column1, column2, ...)
SELECT c.column1, c.column2, ...
FROM dbo.TableC AS c
WHERE EXISTS
(
SELECT 1 FROM dbo.TableA AS a
WHERE a.[Column] = c.[ColumnC]
);
END
GO
You shouldn't use the INSERT TABLE SELECT * FROM TABLE pattern - this is very prone to breaking in the future (see this post for more details). Also see this post about using a schema prefix and these posts about cursor usage - it should be reserved for cases that actually need it, and when you do actually need it, don't use the default options:
https://sqlblog.org/2012/01/26/bad-habits-to-kick-thinking-a-while-loop-isnt-a-cursor
http://www.sqlperformance.com/2012/07/t-sql-queries/running-totals
http://www.sqlperformance.com/2012/09/t-sql-queries/cursor-options
As for why you see rows inserted but then later can't see the data, I suspect you're looking at a table in the wrong database, in the wrong schema, or you have multiple copies of your database (which happens when you use User Instance and AttachDbFileName options in your connection string).