问题:

How to insert more than 4000 characters to CLOB type column?

--create test table s
create table s
(
      a clob
);
insert into s values('>4000 char')

Results in an error:

ORA-01704:the string too long.

When I want to insert string >4000 for one time, how to do it? Is it be possible?

When I read the Oracle reference, CLOB can save max 4GB(Gigabyte)?

回答1:

The maximum for one time insertion is 4000 characters (the maximum string literal in Oracle). However you can use the lob function dbms_lob.append() to append chunks of (maximum) 4000 characters to the clob:

CREATE TABLE don (x clob);


DECLARE 
 l_clob clob;
BEGIN
  FOR i IN 1..10
  LOOP
    INSERT INTO don (x) VALUES (empty_clob()) --Insert an "empty clob" (not insert null)
    RETURNING x INTO l_clob;

    -- Now we can append content to clob (create a 400,000 bytes clob)
    FOR i IN 1..100
    LOOP
      dbms_lob.append(l_clob, rpad ('*',4000,'*'));
      --dbms_lob.append(l_clob, 'string chunk to be inserted (maximum 4000 characters at a time)');
    END LOOP;
  END LOOP;
END;

回答2:

split the long character string into 4000 character or less chunks
create clobs for each chunk using to_clob() function
concatenate the clobs

Here is an example:

insert into <table> (clob_column)
  values
  (
      to_clob(' <=4000 symbols ')
    ||to_clob(' <=4000 symbols ')
    ||to_clob(' <=4000 symbols ')
    ...
    ||to_clob(' <=4000 symbols ')
  );