在MySQL中连接结果值

Question

Can i concat result value and then send the final value as output.

WHILE(LENGTH(totalexpenseamount )>0) DO
        BEGIN
              SET totalshipmentexpenseamount = CONCAT(totalshipmentexpenseamount,',',indshipmentexpenseamount);
END;
    END WHILE;

but at end totalshipmentexpenseamount does not have any value in it.

Answer 1

don't know what is before the code that you presented, but you can try the following:

WHILE(LENGTH(totalexpenseamount )>0) DO
        BEGIN
              SET totalshipmentexpenseamount = CONCAT(COALESCE(totalshipmentexpenseamount, ''),',',indshipmentexpenseamount);
END;
    END WHILE;

this is because totalshipmentexpenseamount is set to null in the first time and when you concat null with other thing it comes out null . The coalesce will return empty if totalshipmentexpenseamount is null

EDIT:

Change to this

WHILE(LENGTH(totalexpenseamount )>0) DO
BEGIN
    SET totalshipmentexpenseamount = COALESCE(CONCAT(totalshipmentexpenseamount,',',indshipmentexpenseamount), indshipmentexpenseamount);
END;
WHILE;

Since you have concatenation with a comma, this will set in the first pass the value of indshipmentexpenseamount otherwise will concat the totalshipmentexpenseamount with a comma and the indshipmentexpenseamount