Problems with function ( UDF ) Not recommended feature: Using SELECT INTO in Scalar UDF

Hello,

I try to create a function in HANA SP10.

This function should lookup into table T001 and return SPRAS column.

My code:

CREATE FUNCTION BUKRS2SPRAS(
 BUKRS NVARCHAR(4) )
RETURNS O_SPRAS NVARCHAR(1)
LANGUAGE SQLSCRIPT --READS SQL DATA 
AS
BEGIN  DECLARE EXIT HANDLER FOR SQLEXCEPTION O_SPRAS := '#';  SELECT T001.SPRAS INTO O_SPRAS FROM T001 T001 WHERE T001.BUKRS = :BUKRS ;
END

I get error " Not recommended feature: Using SELECT INTO in Scalar UDF"

This function should use in a normal sql like

SELECT     X.BUKRS,     BUKRS2SPRAS(X.BUKRS) AS SPRAS
FROM     TABLE AS X

This is only a simple function and I know that I can left outer join table T001 on X,

I would like to understand why this does not work.

Thx for all answers.