SQL UPDATE SET one Column to another value and change value in same step

Question

Take the following update statement.

UPDATE  TABLE_1
SET     Units2 = ABS(Units1)
        ,Dollars2=ABS(Dallars1)
        ,Units1 =0
        ,Dollars1 =0
WHERE Units1 < 0
AND   Dollars2 = 0

Here are my questions,

1) Is this legal? It parses and it "seems" to work (on the test table), but will it always work or am I just picking the right records to review.

2) is there a better way to do this.

Thanks,

Answer 1

It is legal, and as long as you are wanting to essentially keep the old values of Units1 and Dollars1 in Units2 and Dollars2 that should work

Here's a test:

CREATE TABLE #Table_1
(
    Units1 INT,
    Dollars1 MONEY,
    Units2 INT,
    Dollars2 MONEY
)
GO

INSERT INTO #Table_1 (Units1, Dollars1, Units2, Dollars2)
VALUES (-1,12.00,3,0.00)
GO

UPDATE  #TABLE_1
SET     Units2 = ABS(Units1)
        ,Dollars2=ABS(Dollars1)
        ,Units1 =0
        ,Dollars1 =0
WHERE Units1 < 0
AND   Dollars2 = 0
GO

SELECT * 
FROM  #Table_1

Outputs:

Units1 | Dollars1 | Units2| Dollars2
0      | 0.00     | 1     | 12.00