Question

I have a table with columns A,B,C.My requirement is to concatenate the values of columns A and B, and save it into column C.
Note: All columns are of Varchar datatype.

For e.g:

If A = 100 and B = 200, C should be 100200
If A = 0 and B = 200, C should be 0200
If A = NULL AND B = NULL, C should be NULL
If A = NULL and B = 01, C should be  01
If A = 01 and B = NULL, C should be 01

Any ideas how this can be achieved using SQL?If only one of the column values is NULL, result should not be NULL.

What I have so far is:

select A+B C from myTable;

Answer 1

-- return non NULL value when concatenating NULL and non-NULL values
SET CONCAT_NULL_YIELDS_NULL OFF

-- prepare sample data
CREATE TABLE #t (
    A varchar(15),
    B varchar(15),
    C varchar(15)
)

INSERT INTO #t (A, B) VALUES
('100', '200'),
('0', '200'),
(NULL, '200'),
(NULL, NULL),
(NULL, '01'),
('01', NULL)

-- concatenate data
UPDATE #t SET
    C = A + B

-- show
SELECT * FROM #t

-- clean up
DROP TABLE #t