Update trigger in oracle on updating a column
Likewise, use of a view in combination with an INSTEAD OF trigger would likely bomb due to Bug 1992006 (Assuming the use of ODBC, SQL*Loader, Oracle Forms etc.).On the other hand, these issues seem to have been solved by mod_plsql, since I can upload a file directly into a documents table, and the mime_type, doc_size, and last_updated columns all get populated.you do not update the row (the lob locator does not change at all, that is the "lob")insert, update -- doesn't matter, I can get the lob locator after either and modify what it points to -- no triggers fired.
Trying to create a trigger to update the profit whenever record got inserted to the sales table.
As I understand it, you are saying that an "update" to a BLOB column may very well bypass the trigger, since a call to the dbms_lob package can modify the contents of the blob without ever issuing an UPDATE statement.
Thus, one should NEVER create an UPDATE trigger on a BLOB column, since it isn't reliable.
Now I need that feature for the blobs too -but it seems it is very difficult. However, you can use a LOB in the body of a trigger as follows:- in regular triggers old values may be read but not written and new values may not be read nor written.- in 'instead of triggers', the:old and:new values can be read but not written.o dbms_lob.write (and other dbms_lob calls) do not fire a trigger -- people can and will change the value of a blob and you will not be able to detect it with a trigger.
In order to update a LOB, I might never issue an UPDATE. I am a DBA for a large development team, and just received some new ddl that has a table with 2 blob columns.