SQL - safely downcast BIGINT to INT

Question

I have a CSV I\'m importing into our database. One of the \"columns\" contains data that should be an INT but some rows have numbers that only fall in the BIGINT ra

Answer 1

Cast your bigint to varbinary, then store the lower half to @UserID and check the upper half:

• if the upper half is all 0's and the lower half represents a non-negative value, @UserID then contains the correct int value;

• if the upper half is all 1's and @UserID is negative, it's all right too;

• otherwise there's an arithmetic overflow.

Here's an implementation:

DECLARE @UserIDBigInt BIGINT = 9723021913;
DECLARE @UserID INT, @HighInt INT;

WITH v AS (SELECT CAST(@UserIDBigInt AS varbinary) AS bin)
SELECT
  @HighInt = SUBSTRING(bin, 1, 4),
  @UserID  = SUBSTRING(bin, 5, 4)
FROM v;

IF (@HighInt = 0 AND @UserID >= 0 OR @HighInt = -1 AND @UserID < 0) BEGIN
    SELECT 'Handle it as reliable data'
END

Answer 2

I'm not sure this is the best answer but it is one I came up with earlier on my own. It is possible to catch the exception/error and gracefully continue execution.

Example:

DECLARE @UserIDBigInt BIGINT = 9723021913;
DECLARE @UserID INT;
BEGIN TRY
    SET @UserID = @UserIDBigInt;
END TRY BEGIN CATCH
END CATCH

IF @UserID IS NULL BEGIN
    SELECT 'Handle it as unreliable data'
    RETURN
END

SELECT 'Handle it as reliable data'

Answer 3

You could also convert the value to a string, trim it to length and convert to int. not the best way, but a safe easy way for sure

Answer 4

Add these to your script:

SET ARITHABORT OFF;
SET ARITHIGNORE ON;

This will convert any overflow values to NULL.

More info here: http://msdn.microsoft.com/en-us/library/ms184341.aspx