Question

All, I have four columns (A INT, B INT, C INT and D VARCHAR(1)) in a table TableName. I want to move the values from column C to either A or B based upon the value in D. So if D = 'A' I want to move the value in C to A. How can I achieve this?

DECLARE @Column COLUMN;
UPDATE TableName 
SET (@Column = 
    (CASE 
        WHEN D = 'A' THEN A 
        WHEN D = 'B' THEN B
     END)) = C;

Note. I understand the above is madness, but I am trying to express the problem as clearly as possible. I have also exhausted my search for answers. I am not new to SQL but this one has me stumped. Any help is as always, most appreciated.

Answer 1

Here,

UPDATE TableName
SET A = (CASE WHEN D = 'A' THEN C ELSE A END),
    B = (CASE WHEN D = 'B' THEN C ELSE B END)

in this case, only 1 column will be changed since D has only one value at a time.

• SQLFiddle Demo