TO_CHAR (bfile|blob) converts
BLOB data to the database character set. The value returned is always
VARCHAR2. If the value returned is too large to fit into the
VARCHAR2 data type, then the data is truncated.
csid, specify the character set ID of the
BLOB data. If the character set of the
BLOB data is the database character set, then you can specify a value of 0 for
csid, or omit
Appendix C in Oracle Database Globalization Support Guide for the collation derivation rules, which define the collation assigned to the character return value of this function
The following hypothetical example takes as its input a
media_col in table
media_tab, which uses the character set with ID 873. The example returns a
VARCHAR2 value that uses the database character set.
SELECT TO_CHAR(media_col, 873) FROM media_tab;