Error creating function in DB2 with params - sql

Question

I have a problem with a function in db2
The function finds a record, and returns a number according to whether the first and second recorded by a user
The query within the function is this
SELECT
CASE
WHEN NUM IN (1,2) THEN 5
ELSE 2.58
END AS VAL
FROM (
select ROW_NUMBER() OVER() AS NUM ,s.POLLIFE
from LQD943DTA.CAQRTRML8 c
INNER JOIN LSMODXTA.SCSRET s ON c.MCCNTR = s.POLLIFE
WHERE s.NOEMP = ( SELECT NOEMP FROM LSMODDTA.LOLLM04 WHERE POLLIFE = '0010111003')
) AS T WHERE POLLIFE = '0010111003'
And works perfect
I create the function with this code
CREATE FUNCTION LIBWEB.BNOWPAPOL(POL CHAR)
RETURNS DECIMAL(7,2)
LANGUAGE SQL
NOT DETERMINISTIC
READS SQL DATA
RETURN (
SELECT
CASE
WHEN NUM IN (1,2) THEN 5
ELSE 2.58
END AS VAL
FROM (
select ROW_NUMBER() OVER() AS NUM ,s.POLLIFE
from LQD943DTA.CAQRTRML8 c
INNER JOIN LSMODXTA.SCSRET s ON c.MCCNTR = s.POLLIFE
WHERE s.NOEMP = ( SELECT NOEMP FROM LSMODDTA.LOLLM04 WHERE POLLIFE = POL)
) AS T WHERE POLLIFE = POL
)
The command runs executed properly
WARNING: 17:55:40 [CREATE - 0 row(s), 0.439 secs] Command processed.
No rows were affected
When I want execute the query a get a error
SELECT LIBWEB.BNOWPAPOL('0010111003') FROM DATAS.DUMMY -- dummy has only one row
I get
[Error Code: -204, SQL State: 42704] [SQL0204] BNOWPAPOL in LIBWEB
type *N not found.
I detect, when I remove the parameter the function works fine!
With this code
CREATE FUNCTION LIBWEB.BNOWPAPOL()
RETURNS DECIMAL(7,2)
LANGUAGE SQL
NOT DETERMINISTIC
READS SQL DATA
RETURN (
SELECT
CASE
WHEN NUM IN (1,2) THEN 5
ELSE 2.58
END AS VAL
FROM (
select ROW_NUMBER() OVER() AS NUM ,s.POLLIFE
from LQD943DTA.CAQRTRML8 c
INNER JOIN LSMODXTA.SCSRET s ON c.MCCNTR = s.POLLIFE
WHERE s.NOEMP = ( SELECT NOEMP FROM LSMODDTA.LOLLM04 WHERE POLLIFE = '0010111003')
) AS T WHERE POLLIFE = '0010111003'
)
Why??

Answer 1

This statement:
SELECT LIBWEB.BNOWPAPOL('0010111003') FROM DATAS.DUMMY
causes this error:
[Error Code: -204, SQL State: 42704] [SQL0204] BNOWPAPOL in LIBWEB
type *N not found.
The parm value passed into the BNOWPAPOL() function is supplied as a quoted string with no definition (no CAST). The SELECT statement assumes that it's a VARCHAR value since different length strings might be given at any time and passes it to the server as a VARCHAR.
The original function definition says:
CREATE FUNCTION LIBWEB.BNOWPAPOL(POL CHAR)
The function signature is generated for a single-byte CHAR. (Function definitions can be overloaded to handle different inputs, and signatures are used to differentiate between function versions.)
Since a VARCHAR was passed from the client and only a CHAR function version was found by the server, the returned error fits. Changing the function definition or CASTing to a matching type can solve this kind of problem. (Note that a CHAR(1) parm could only correctly handle a single-character input if a value is CAST.)