MX 2.x)

Deleting CLOB Data

To delete CLOB data, the JDBC application uses the SQL DELETE statement to delete the row in the base table.

When the row containing the CLOB column is deleted by the JDBC application, the corresponding CLOB data is

automatically deleted by the delete trigger associated with the base table. For information about triggers, see Using an

SQL/MX Trigger to Delete LOB Data.

See also NULL and Empty BLOB or CLOB Value.

Storing BLOB Data

You can perform operations similar to those used on CLOB columns as those used on BLOB columns by using the Blob

interface. You can:

Use the EMPTY_BLOB() function in the insert statement to create an empty BLOB column in the database.

Use setBinaryStream method of the Blob interface to obtain the InputStream to read BLOB data.

Use getBinaryStream method of the Blob interface to obtain the OutputStream to write BLOB data.

Use setBinaryStream of the PreparedStatement interface to write the data to the BLOB column.

The details of these operations are discussed in the following topics:

Inserting a BLOB Column Using the Blob Interface

Writing Binary Data to a BLOB Column

Inserting a BLOB Column by Using the PreparedStatement Interface

Inserting a Blob Object by Using the setBlob Method

Inserting a BLOB Column by Using the Blob Interface

When you insert a row containing a BLOB data type, you can insert the row with an "empty" BLOB value before the

column can be updated with real BLOB data. You can insert an empty BLOB value in an SQL/MX database by specifying

EMPTY_BLOB() function for the BLOB column in the insert statement.

The JDBC/MX driver scans the SQL string for the EMPTY_BLOB() function and substitutes the next-available data

locator.

Then, you must obtain the handle to the empty BLOB column by selecting the BLOB column for update.

The following code illustrates how to obtain the handle to an empty BLOB column:

Blob myBlob = null;

Statement s = conn.createStatement();

ResultSet rs = s.executeQuery("Select myBlobColumn

from myTable where …For update");

if (rs.next())

myBlob = rs.getBlob(1);

You can now write data to the BLOB column. See Writing Binary Data to a BLOB Column.