Oracle BLOB Field Update Guide

To update the value of a BLOB field, you can use the UPDATE statement to insert new BLOB data into the corresponding field. Here is an example SQL statement:

UPDATE your_table
SET your_blob_column = empty_blob()
WHERE your_condition;

SELECT your_blob_column
INTO your_blob_variable
FROM your_table
WHERE your_condition
FOR UPDATE;

UPDATE your_table
SET your_blob_column = your_blob_variable
WHERE your_condition;

In this example, the first step is to set the BLOB field to an empty BLOB using an UPDATE statement. Then, the SELECT INTO statement is used to store the BLOB data that needs to be updated into a variable. Finally, another UPDATE statement is used to update the BLOB data from the variable back into the corresponding field. Make sure to lock the relevant rows using FOR UPDATE to prevent inconsistencies in the data due to concurrent updates when updating BLOB fields.