Combining strings in DB2 Stored Procedure - sql

Question

I was wondering how to combine Varchar variables in a stored procedure. I want to combine email addresses into a single variable based of access level. I have tried doing a few things in my if statement.
For example I have tried both:
v_m1_email = Concat(v_m1_email, ' , ' , v_email)
and
v_m1_email = v_m1_email || ' , ' || v_email
My code:
CREATE PROCEDURE ALERTEMAIL (OUT p_m1_email VARCHAR(300),
OUT p_m2_email VARCHAR(300),
OUT p_m3_email VARCHAR(300),
OUT p_m4_email VARCHAR(300))
DYNAMIC RESULT SETS 1
P1: BEGIN
DECLARE v_email VARCHAR(50);
DECLARE v_access CHAR(5);
DECLARE v_m1_email VARCHAR(300);
DECLARE v_m2_email VARCHAR(300);
DECLARE v_m3_email VARCHAR(300);
DECLARE v_m4_email VARCHAR(300);
DECLARE SQLSTATE CHAR(5);
DECLARE cursor1 CURSOR WITH RETURN for
SELECT EMAIL,JOB_ID FROM PERSONNEL;
OPEN cursor1;
FETCH cursor1 INTO v_email, v_access;
WHILE (SQLSTATE = '00000') DO
IF v_access = 'Man1' THEN
SET v_m1_email = v_m1_email + ' , ' + v_email;
ELSEIF v_access = 'Man2' THEN
SET v_m2_email = v_m2_email + ' , ' + v_email;
ELSEIF v_access = 'Man3' THEN
SET v_m3_email = v_m3_email + ' , ' + v_email;
ELSEIF v_access = 'Man4' THEN
SET v_m4_email = v_m4_email + ' , ' + v_email;
END IF;
FETCH cursor1 INTO v_email, v_access;
END WHILE;
SET p_m1_email = v_m1_email;
SET p_m2_email = v_m2_email;
SET p_m3_email = v_m3_email;
SET p_m4_email = v_m4_email;
END P1

Answer 1

With regard to the first of what already had been tried from the OP, just as #I_am_Batman on 23-Apr-2016 already noted, the syntax for the CONCAT scalar >>-CONCAT--(--expression1--,--expression2--)------>< is limited to just the two arguments, so the expression coded as Concat(v_m1_email, ' , ' , v_email) would fail, presumably with a sqlcode=-170 suggesting something like "Number of arguments for function CONCAT not valid."
Which variant of DB2 was not noted [not in tag nor by comment in the OP], but I offer this link to some doc DB2 for Linux UNIX and Windows 9.7.0->Database fundamentals->SQL->Functions->Scalar functions->CONCAT
However there is nothing conspicuously incorrect with the second of what already had been tried from the OP; i.e. assuming the assignment and expression shown, had been coded just as shown in the body of the CREATE PROCEDURE, with a preceding SET and a trailing ;. In that case, the statement SET v_m1_email = v_m1_email || ' , ' || v_email; should have been able to pass both syntax-checking and data-type\validity-checking. Whereas what is shown in the OP as SET v_m1_email = v_m1_email + ' , ' + v_email; is not valid except when the values of both variables always would be valid string-representations of numbers; that is because the + operator is a numeric-operator rather than the [conspicuously as-desired] string-operator used to effect concatenation [i.e. for "combining strings"].
[ed: 22-Aug-2016] I forgot there was a constant\literal ' , ' in the above expression, so that string-literal also would have to evaluate as a numeric to allow that expression with the + as addition-operator to function at run-time. But of course, that literal could never be interpreted as a numeric; so while the expression could be treated as valid for compile-time [with implicit cast in effect and data-checking not examining the literal value], that expression never would be capable of being evaluated at run-time.
Therefore, if the || operator was properly coded [as seems so, given what was claimed to have been "tried"], yet did not effect what was desired, then the OP would need to be updated to state exactly what was the problem. For example, perhaps there was an error in compile\CREATE of the routine, or perhaps a run-time error for which the effect of the concatenation was perhaps untrimmed results or some other unexpected output, or something else.?.?
Note: as I already added in a comment to a prior answer, the use of CONCAT operator vs the equivalent || in SQL source enables use of that source in\across other code pages without a possible issue due to the use of a variant character.
p.s. A CASE statement might be preferred in place of the IF\ELSE constructs
p.p.s. Might be worth review if the SP really should return both the RS and, or just, the OUT parameters

Answer 2

String concatenation can be done with the || operator.
set vEmail = userName || '#' || domain || '.' || tld;
Give that a try.