DBMS_OUTPUT in Oracle

Oracle built in with a set of built-in packaged procedures that provide a wealth of functionality for DBA's and developers.

DBMS_OUTPUT

You can use this standard packaged procedure to write messaged to the buffer area and later retrieve those messages.
One of the remarkable usage of this packaged procedure is it capability to display the buffer to your screen if you are using SQLDBA or SQLPLUS.

DBMS_OUTPUT.PUT_LINE(message varchar2);

This procedure is used to Write a message to the session's buffer. You can invoke DBMS_OUTPUT.PUT_LINE(message). either within a PL/SQL block or directly from SQL prompt.

DBMS_OUTPUT.GET_LINE( Message out Varchar2 , Status out integer)
Once this procedure is executed it will return the buffer line into the (Message) variable and will return the Status into the (Status) variable. If a line of information is found in the buffer, the procedure will return a zero in the Status variable, otherwise status is <> 0

What is ROWID in Oracle?

The ROWID is a unique database-wide physical address for every row on every table. Once assigned (when the row is first inserted into the database), it never changes until the row is deleted or the table is dropped.

The ROWID consists of the following three components, the combination of which uniquely identifies the physical storage location of the row.

* Oracle database file number, which contains the block with the rows
* Oracle block address, which contains the row
* The row within the block (because each block can hold many rows)

The ROWID is used internally in indexes as a quick means of retrieving rows with a particular key value. Application developers also use it in SQL statements as a quick way to access a row once they know the ROWID