I'm trying to run a query that has a few columns that are a CLOB datatype. If i run the query like normal, all of those fields just have (CLOB) as the value.
I tried using DBMS_LOB.substr(column) and i get the error
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
How can i query the CLOB column?
If you are using SQL*Plus try the following...
set long 8000
select ...
To add to the answer.
declare
v_result clob;
begin
---- some operation on v_result
dbms_lob.substr( v_result, 4000 ,length(v_result) - 3999 );
end;
/
In dbms_lob.substr
first parameter is clob which you want to extract .
Second parameter is how much length of clob you want to extract.
Third parameter is from which word you want to extract .
In above example i know my clob size is more than 50000 , so i want last 4000 character .
I did run into another condition with HugeClob in my Oracle database. The dbms_lob.substr only allowed a value of 4000 in the function, ex:
dbms_lob.substr(column,4000,1)
so for my HughClob which was larger, I had to use two calls in select:
select dbms_lob.substr(column,4000,1) part1,
dbms_lob.substr(column,4000,4001) part2 from .....
I was calling from a Java app so I simply concatenated part1 and part2 and sent as a email.
If it's a CLOB why can't we to_char the column and then search normally ?
Create a table
CREATE TABLE MY_TABLE(Id integer PRIMARY KEY, Name varchar2(20), message clob);
Create few records in this table
INSERT INTO MY_TABLE VALUES(1,'Tom','Hi This is Row one');
INSERT INTO MY_TABLE VALUES(2,'Lucy', 'Hi This is Row two');
INSERT INTO MY_TABLE VALUES(3,'Frank', 'Hi This is Row three');
INSERT INTO MY_TABLE VALUES(4,'Jane', 'Hi This is Row four');
INSERT INTO MY_TABLE VALUES(5,'Robert', 'Hi This is Row five');
COMMIT;
Search in the clob column
SELECT * FROM MY_TABLE where to_char(message) like '%e%';
Results
ID NAME MESSAGE
===============================
1 Tom Hi This is Row one
3 Frank Hi This is Row three
5 Robert Hi This is Row five
For big CLOB selects also can be used:
SELECT dbms_lob.substr( column_name, dbms_lob.getlength(column_name), 1) FROM foo
Another option is to create a function and call that function everytime you need to select clob column.
create or replace function clob_to_char_func
(clob_column in CLOB,
for_how_many_bytes in NUMBER,
from_which_byte in NUMBER)
return VARCHAR2
is
begin
Return substrb(dbms_lob.substr(clob_column
,for_how_many_bytes
,from_which_byte)
,1
,for_how_many_bytes);
end;
and call that function as;
SELECT tocharvalue, clob_to_char_func(tocharvalue, 1, 9999)
FROM (SELECT clob_column AS tocharvalue FROM table_name);
This works
select DBMS_LOB.substr(myColumn, 3000) from myTable
Source: Stackoverflow.com