New Function in Oracle BI

Question

Hi :)
I made a new function in PL/SQL transfering BLOB to CLOB.
i made this function, because I know how to translate CLOB in Oracle BI.
with this function for example:
EVALUATE('DBMS_LOB.SUBSTR(%1,40,1)',PACKET_CONTENTS)
but in my case, this Packet_content is BLOB, so i want to translate it to CLOB and than use the substr function to translate it (or part of it).
so I tried doing that:
EVALUATE('DBMS_LOB.SUBSTR(%1,40,1)',EVALUATE('BLOB_2_CLOB(%1)','111'))
the parameter "111" is a param i give to my function (just for test). and my function should return the results from the PACKET_CONTENTS in CLOB type.
the answer error i get is the following one:
State: HY000. Code: 10058. [NQODBC] [SQL_STATE: HY000] [nQSError: 10058] A general error has occurred. [nQSError: 14027] The navigator cannot handle the following request containing constants only: Evaluate( DBMS_LOB.SUBSTR(%1,40,1),Evaluate( BLOB_2_CLOB(%1),'111') ) as c1. (HY000)
SQL Issued: SELECT EVALUATE('DBMS_LOB.SUBSTR(%1,40,1)',EVALUATE('BLOB_2_CLOB(%1)','111')) saw_0 FROM RWD ORDER BY saw_0
Any ideas? or any other information you want to know?
thanks :)
P.S: im really new in the Oracle BI things, so I might be do silly things I cant do... so please fix me if you can :)
thanks !

Answer 1

Are you trying to return a text string from the BLOB/CLOB? Can you not do this in a database view over the top of your existing table, removing any potential ODBC/OCI issues?
ie.
CREATE VIEW test_view AS
SELECT dbms_lob.substr( blob_column,4000,1) text_column
FROM <table>;