MX 2.x)

Reading Unicode Data from a CLOB Column

You can read Unicode data from the CLOB column by using the Clob interface or Reader. The following code

illustrates how to read the Unicode data from the CLOB column by using the Clob interface.

// Obtain the Clob from ResultSet

Clob myClob = rs.getClob("myClobColumn");

// Obtain the input stream to read Clob data

Reader cs = myClob.getCharacterStream();

// read Clob data using Reader

char[] myClobData = new char[length];

int readLen = cs.read(myClobData, offset, length);

To read Unicode data from the CLOB column by using a Reader:

// obtain the Reader from ResultSet

Reader cs = rs.getCharacterStream("myClobColumn");

// read Clob data using the InputStream

char[] myClobData = new char[length];

int readLen = cs.read(myClobData, offset, length);

Updating CLOB Data

You can make updates to CLOB data by using the methods in the Clob interface or by using the updateClob method of

the ResultSet interface. The JDBC/MX driver makes changes directly to the CLOB data. Therefore, the JDBC/MX

driver returns false to the locatorsUpdateCopy method of the DatabaseMetaData interface. Applications do not need

to issue a separate update statement to update the CLOB data.

Make updates to CLOB data in the following ways:

Updating Clob Objects with the updateClob Method

Replacing Clob Objects

Updating Clob Objects with the updateClob Method

Unlike some LOB support implementations, the JDBC/MX driver updates the CLOB data directly in the database. So,

when the Clob object is the same in the updateClob method as the Clob object obtained using getClob, the

updateRow method of the ResultSet interface does nothing with the Clob object.

When the Clob objects differ, the Clob object in the updateClob method behaves as if the setClob method was issued.

See Inserting a Clob Object with the setClob Method.

Replacing Clob Objects

You can replace Clob objects in the following ways:

Use the EMPTY_CLOB() function to replace the Clob object with the empty Clob object, then insert new data as

described under Inserting CLOB Columns by Using the Clob Interface.

Use the PreparedStatement.setAsciiStream() or setCharacterStream() method to replace the existing Clob

object with new CLOB data.

Use the setClob or updateClob method to replace the existing CLOB objects as explained earlier under Inserting

a Clob Object with the setClob Method and Updating Clob Objects with the updateClob Method.