Re: some problem with CLOB

Thomas Kellerer <>
Wed, 10 Sep 2008 10:22:17 +0200
<>, 10.09.2008 04:35:

I have a oracle table with a CLOB field named NEWS_CONTETN, and I want
put some news information which may be larger than 4k, I have searched
for some example and take following steps:

1. insert an empty clob to the table
sql1="insert into TAB1(id,COL_CLOB) values(1,empty_clob())";

2. initialize a CLOB variable and select the clob field for update

sql2="select COL_CLOB from TAB1 where id=1 for update";
oracle.sql.CLOB clob=null;

3. put the news information to the CLOB variable
in step 3, i have tried 3 ways, but it didn't work :(
(1) clob.putChars(1,newsStr.toString().toCharArray()); //newsStr is
a string
(2) out = clob.setAsciiStream(0);
(3) Writer outStream = clob.getCharacterOutputStream();

4. update the table
sql3="update TAB1 set COL_CLOB=? where id='1'";

I can't use any method of oracle.sql.CLOB, and get an exception null
what should i do? pls anyone help me, thanks in advance!

First of all: make sure you use an Oracle 10.x driver. The Oracle 9.x drivers do not support LOBs in a decent fashion.

1) Insert (or update) a CLOB

String sql = "insert into tab1 (col_clob) values (?)";
String myLongClobContent = " ... whatever ...";
StringReader r = new StringReader(myLongClobContent);
PreparedStatement stmt = connection.prepareStatement(sql);
stmt.setCharacterStream(1, r, myLongClobContent.length());

2) to read a CLOB

String sql = "SELECT col_clob FROM tyb1";
Statement stmt = connection.createStatement();
ResultSet rs = stmt.executeQuery(sql);
while (
  Reader in = rs.getCharacterStream(1);
  // read from the stream into a String variable

  // or simply use getString(1), I think that is supported by newer drivers as well.

Again: make sure your driver version is at least 10.1


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