How to continue cursor loop even error occured in the loop

Question

I want to insert rows of one table into another. For that I have the below procedure.

ALTER PROCEDURE LOADDATA_a
AS 
BEGIN

TRUNCATE TABLE STIDENT_A
DECLARE @SID INT
DECLARE @SNAME VARCHAR(50)
DECLARE @SUB VARCHAR(50)
DECLARE @MARKS INT

DECLARE LOAD_DATA CURSOR FAST_FORWARD FOR  
SELECT SID,SNAME,SUB,MARKS 
FROM student 

OPEN LOAD_DATA   
FETCH NEXT FROM LOAD_DATA INTO @SID,@SNAME,@SUB,@MARKS

WHILE @@FETCH_STATUS = 0   
BEGIN
    BEGIN TRANSACTION

    INSERT INTO STIDENT_A(SID,SNAME,SUB,MARKS) VALUES (@SID,@SNAME,@SUB,@MARKS)

    IF @@ERROR != 0
    BEGIN
        ROLLBACK TRANSACTION
        RETURN
    END
    ELSE
    BEGIN
        COMMIT TRANSACTION
    END
    FETCH NEXT FROM LOAD_DATA INTO @SID,@SNAME,@SUB,@MARKS
END

CLOSE LOAD_DATA   
DEALLOCATE LOAD_DATA

END

Whenever a row fails to insert, the cursor fails and stops there, but I need it to continue. How to do that?

Answer 1

Apparently, you've got a RETURN statement immediately after ROLLBACK TRANSACTION. Have you tried just removing it?

Although you could also rewrite the body using TRY/CATCH instead, like this:

...
WHILE @@FETCH_STATUS = 0   
BEGIN
    BEGIN TRY
        INSERT INTO STIDENT_A(SID,SNAME,SUB,MARKS)
        VALUES (@SID,@SNAME,@SUB,@MARKS);
    END TRY
    BEGIN CATCH
      -- this section must have some statement,
      -- so, why not log the erroneous data to the screen at least?
      PRINT @SID;
      PRINT @SNAME;
      PRINT @SUB;
      PRINT @MARKS;
      PRINT '';  -- an empty line as a delimiter
      -- or, perhaps, into a table?
      --INSERT INTO SomeFailLog (SID,SNAME,SUB,MARKS)
      --VALUES (@SID,@SNAME,@SUB,@MARKS);
    END CATCH;
    FETCH NEXT FROM LOAD_DATA INTO @SID,@SNAME,@SUB,@MARKS;
END;
...

But if you know what specifically may cause the inserts to fail, it might be even better to come up with a single statement that would produce only valid data to insert.

For instance, if the issue is that some SIDs in student already exist in STIDENT_A and you need to omit them, you could simply try the following instead of your procedure:

INSERT INTO STIDENT_A (SID, SNAME, SUB, MARKS)
SELECT s.SID, s.SNAME, s.SUB, s.MARKS
FROM student AS s
LEFT JOIN STIDENT_A AS a ON s.SID = a.SID
WHERE a.SID IS NULL
;

If you specify what exactly may be the issue while transferring your data, we might be able to help you with finding the most efficient solution specifically for that.

---

UPDATE addressing the comments

If the issue is that the maximum length of SNAME in STIDENT_A is less than that of the same name column in student and some values may not fit, you could simply use a filter (a WHERE clause) to limit the inserted rows to those where the actual length of SNAME does not exceed a certain value:

INSERT INTO STIDENT_A (SID, SNAME, SUB, MARKS)
SELECT SID, SNAME, SUB, MARKS
WHERE LEN(SNAME) <= @maxlength
;

You could query the metadata to determine the maximum length of the required column. There are various ways, one is to use the sys.columns system catalog:

DECLARE @maxlength int;
SELECT @maxlength = max_length
FROM sys.columns
WHERE object_id = OBJECT_ID('STIDENT_A')
  AND name = 'SNAME'
;

To determine which rows could not be inserted:

INSERT INTO STIDENT_A (SID, SNAME, SUB, MARKS)
SELECT SID, SNAME, SUB, MARKS
WHERE LEN(SNAME) > @maxlength
;

Answer 2

Try This:-

DECLARE @intFlag INT
 SET @intFlag = 0
WHILE (@intFlag <=5)
BEGIN
    begin Try
        if @intFlag = 3
        begin
            SET @intFlag = @intFlag + 'A'
        End
    Else
        begin
            PRINT @intFlag
        end
    End Try

    Begin Catch
        --print 'Error'
        -- continue
    End catch
SET @intFlag = @intFlag + 1
END
GO