JDBC Type 4 Driver Programmer's Reference for SQL/MX Release 3.2.1

// read Blob data using the InputStream
byte[] myBlobData;
myBlobData = new byte[length];
is.read(myBlobData, offset, length);
Using InputStream:
// obtain the InputStream from ResultSet
InputStream is = rs.getBinaryStream("myBlobColumn");
// read Blob data using the InputStream
byte[] myBlobData;
myBlobData = new byte[length];
is.read(myBlobData, offset, length);
Updating BLOB Data
To update BLOB data, use the methods in the Blob interface or use the updateBlob method of
the ResultSet interface. The Type 4 driver makes changes to the BLOB data directly. Therefore,
the Type 4 driver returns false to the locatorsUpdateCopy method of the DatabaseMetaData
interface. Applications do not need to issue a separate update statement to update the BLOB data.
Update BLOB data in the following ways.
• “Updating Blob Objects by Using the updateBlob Method” (page 62)
• “Replacing Blob Objects” (page 62)
Updating Blob Objects by Using the updateBlob Method
Unlike some LOB support implementations, the Type 4 driver updates the BLOB data directly in
the database. So, when the Blob object is same in the updateBlob method as the object obtained
using getBlob, the updateRow method of the ResultSet interface does nothing with the Blob
object.
When the Blob objects differ, the Blob object in the updateBlob method behaves as if the
setBlob method was issued. See Inserting a Blob Object with the setBlob Method.
Replacing Blob Objects
You can replace Blob objects in the following ways:
• Use the EMPTY_BLOB() function to replace the Blob object with the empty Blob object.
• Replace an existing Blob object in a row by inserting the Blob with new data as described
under Inserting a BLOB Column Using the Blob Interface.
• Use the setBinaryStream() method of the PreparedStatement interface to replace
the existing Blob object with new BLOB data.
• Use the setBlob or updateBlob methods to replace the existing BLOB objects as explained
under Inserting a Blob Object with the setBlob Method and Updating Blob Objects with the
UpdateBlob Method.
Deleting BLOB Data
To delete BLOB data, the JDBC application uses the SQL DELETE statement to delete the row in the
base table.
When the row containing the BLOB column is deleted by the application, the corresponding BLOB
data is automatically deleted by the delete trigger associated with the base table. For information
about triggers, see Using SQL/MX Triggers to Delete LOB Data.
See also “NULL and Empty BLOB or Empty CLOB Value” (page 63).
62 Working with BLOB and CLOB Data