Question: I need to export only my table and
index definitions for my schema. What are the ways to export
only the metadata definitions and not export the data? How do
I convert a blob to a clob?
Answer: This PL/SQL function script will
convert a BLOB into a CLOB. The convert function
accepts a BLOB as input and returns a CLOB datatype. We
can use two methods to convert a BLOB to a CLOB:
- dbms_lob.converttoclob
- utl_raw.cast_to_varchar2
For example, here we use
dbms_lob.converttoclob to convert a BLOB to a CLOB:
dbms_lob.converttoclob Tips
Here we convert a BLOB to a CLOB using
utl_raw.cast_to_varchar2 :
Select blob_to_clob(blob_column) from
table_name;
-- PL/SQL
function to convert a BLOB to a CLOB
CREATE OR REPLACE
FUNCTION blob_to_clob (blob_in IN BLOB)
RETURN CLOB
AS
v_clob CLOB;
v_varchar VARCHAR2(32767);
v_start PLS_INTEGER := 1;
v_buffer PLS_INTEGER := 32767;
BEGIN
DBMS_LOB.CREATETEMPORARY(v_clob, TRUE);
FOR i IN
1..CEIL(DBMS_LOB.GETLENGTH(blob_in) / v_buffer)
LOOP
v_varchar :=
UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(blob_in, v_buffer,
v_start));
DBMS_LOB.WRITEAPPEND(v_clob,
LENGTH(v_varchar), v_varchar);
v_start := v_start + v_buffer;
END LOOP;
RETURN v_clob;
END blob_to_clob;
/