Why does this SQL stored procedure require that a temp table be created for it to work (return results)? - sql

Question

IBM Informix Dynamic Server Version 11.50.FC6
I was working on a small stored procedure that would take name fields from a table and parse them into "user names" with a maximum of 8 chars.
This is the code I was trying:
CREATE PROCEDURE build_jics_user (pid INT)
RETURNING CHAR(8) AS username;
SELECT LOWER((SUBSTR(firstname,0,1))||(SUBSTR(lastname,0,7))) username
FROM id_rec
WHERE id = pid;
END PROCEDURE;
The error returned when executed is:
659: INTO TEMP table required for SELECT statement.
Error in line 5
Near character position 15
I don't understand what the point of summoning a temporary table is, and I also couldn't find any similarly simple examples online that would work without error.
Does anyone know what I'm missing?

Answer 1

What you want to say is this:
CREATE PROCEDURE build_jics_user (pid INT)
RETURNING CHAR(8);
DEFINE username CHAR(8);
SELECT LOWER((SUBSTR(firstname,0,1))||(SUBSTR(lastname,0,7))) INTO username
FROM id_rec
WHERE id = pid;
RETURN username;
END PROCEDURE;
... and execute it like this:
EXECUTE PROCEDURE build_jics_user(42);
UPDATE
If the purpose of this is to be a function, where it's required inside some other SQL, then you might do the following:
CREATE FUNCTION jics_user(fname VARCHAR(255), lname VARCHAR(255))
RETURNING CHAR(8);
RETURN LOWER(SUBSTR(fname,0,1) || SUBSTR(lname,0,7));
END FUNCTION;
... and execute it like this:
SELECT id, firstname, lastname, jics_user(firstname, lastname) AS jics_user, ...
FROM id_rec;
There's no real technical difference between a PROCEDURE and a FUNCTION, it's more an assertion as to how it's used.

Answer 2

This seems to be per design (which must be accounting for the absence of the 'similarly simple examples online'). Apparently, whatever data you are pulling with a SELECT statement in a stored procedure, you cannot return them directly. You should store them either in a temporary table or in variables for later use.
It is likely that your SELECT statement should look like this
SELECT LOWER((SUBSTR(firstname,0,1))||(SUBSTR(lastname,0,7))) INTO username
FROM id_rec
WHERE id = pid;