Download PL/SQL Programming Chapter 9 Oracle

Oracle9i Developer:
PL/SQL Programming
Chapter 9
Oracle-Supplied
Packages
Objectives
• Use communications packages
• Generate output via packages
• Include large objects in the Oracle
database
• Explore dynamic SQL and PL/SQL
• Identify other important built-in packages
Brewbean’s Challenge
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Credit card verification
Real-time messages
E-mail generation
Import external file data
Include image files in the database
Schedule program execution
Communications Packages
Built-in Package
Name
Description
Script
Filename
DBMS_PIPE
Allows different
database sessions
to communicate
dbmspipe.sql
DBMS_ALERT
Enables
notification of
database events
dbmsalrt.sql
UTL_SMTP
Enables e-mail
features
utlsmtp.sql
DBMS_PIPE
• Allows different sessions in the same
instance to communicate
• Uses buffers in the SGA
• Typically used to interface with the
operating system or an external system
• Sending a message is a two step
process of packing and sending
DBMS_PIPE Example
DBMS_ALERT
• Allows real-time messages or alerts to
be sent to users upon a particular event
• Accomplished in a database trigger to
be associated with an event
• An example use is online auctions
• Process includes: register an alert
name, set when alert should signal, and
identify users that should be recipients
DBMS_ALERT Example
• Register name:
DBMS_ALERT.REGISTER(‘new_bid’);
• Fire signal in database trigger:
DBMS_ALERT.SIGNAL(‘new_bid’, TO_CHAR(:new.bid));
• Register recipient:
DBMS_ALERT.WAITONE(‘new_bid’, v_msg,
v_status, 600);
UTL_SMTP
• Simplifies e-mail generation
• Simple Mail Transfer Protocol (SMTP)
used to send e-mails
• Programmatically create all the parts of
an e-mail
• Used to communicate with customers,
suppliers, and internal employees as
appropriate
UTL_SMTP
Function Name
Description
HELO
Performs initial handshaking to identify the sender to the mail
server
MAIL
Initiates a mail transaction which sends messages to mailbox
destinations
RCPT
Identifies each of the recipients of an e-mail
DATA
Specifies the lines in the body of an e-mail
RSET
Aborts the current mail transaction
NOOP
Requests a reply from the mail server to verify connection is
still alive
QUIT
Terminates the SMTP session and disconnects from the mail
server
OPEN_CONNECTION
Opens a connection to the mail server
OPEN_DATA
Sends the DATA command
WRITE_DATA
Adds data to message body
CLOSE_DATA
Ends the message
UTL_HTTP
• Used to analyze HTML source of Web
pages
• Makes Hypertext Transfer Protocol
(HTTP) calls from within PL/SQL
• REQUEST_PIECES function will
retrieve the HTML source of a specified
URL in 2,000 byte segments
UTL_TCP
• Allows low-level calls using TCP/IP
• Internet communications rely on
TCP/IP
• The UTL_SMTP and UTL_HTTP
packages rely on this package
Generating Output
Built-in Package Name
Description
Script Filename
DBMS_OUTPUT
Displays data to the screen
dbmsotpt.sql
UTL_FILE
Read and write data to
external files
utlfile.sql
DBMS_OUTPUT
• Displays data from within PL/SQL code
• Most popularly used for debugging
• In SQL*Plus, SET SERVEROUTPUT
ON must be set
• The PUT procedure continues to place
data on the same output line
• The PUT_LINE procedure will start a
new line
DBMS_OUTPUT Example
UTL_FILE
• Enables reading and writing text data to
operating system files (import and
export data)
Program Unit Name
Description
FOPEN
Opens a file to write to or be read
PUT_LINE
Writes a line to a file
GET_LINE
Reads a line from a file
FCLOSE
Closes a file
UTL_FILE Example
• Write to a file:
UTL_FILE Example
• Read a file:
Large Objects (LOBs)
• Handle media such as images, video
segments, and large documents
LOB Type
Description
BLOB
Binary large object such as a photo file
CLOB
Character large object such as text documentation
BFILE
Binary large object such as a streaming video or
movie file
NCLOB
Fixed-width character data for storing character data
in other languages
LOBs
• Enable the storage of large objects as
columns in a database table
• Can hold up to 4GB of data
• Multiple LOB columns allowed
• All except BFILE are stored internally in
the database
• A LOB column contains pointer to actual
LOB data
DBMS_LOB Example
Dynamic SQL and PL/SQL
• Allow construction and parsing of
statements at runtime
• Enable the execution of DDL statements
from within PL/SQL
• Two mechanisms:
– DBMS_SQL package
– Dynamic SQL
• Covered in Chapter 10
DBMS_JOB
• Enables jobs to be scheduled for
execution
Program Unit Name
Description
BROKEN
Flags the job as broken so it will not be executed
CHANGE
Alters job parameters set by a user
INTERVAL
Modifies execution interval for a job
ISUBMIT
Submits a job with a specified job number
NEXT_DATE
Modifies the next date of execution
REMOVE
Deletes job from the queue
RUN
Executes the specified job immediately
SUBMIT
Adds a job to the queue
USER_EXPORT
Creates text of call to recreate the job
WHAT
Modifies the PL/SQL code to be executed
DBMS_JOB
• INIT.ORA settings:
JOB_QUEUE_PROCESSES=1
JOB_QUEUE_INTERVAL=60
• SUBMIT procedure:
PROCEDURE submit
( job
OUT BINARY_INTEGER,
what
IN VARCHAR2,
next_date IN DATE DEFAULT sysdate,
interval IN VARCHAR2 DEFAULT 'null',
no_parse IN BOOLEAN DEFAULT FALSE,
instance IN BINARY_INTEGER DEFAULT 0,
force
IN BOOLEAN DEFAULT FALSE );
DBMS_JOB Example
BEGIN
DBMS_JOB.SUBMIT
(job => :jobno,
what => 'BEGIN prod_sum_sp; END;',
next_date => TRUNC(SYSDATE+1),
interval => 'TRUNC(SYSDATE+1)' );
COMMIT;
END;
/
DBMS_JOB Example
DBMS_DDL
• Allows access to two specific DDL
statements:
– ALTER_COMPILE
– ANALYZE_OBJECT
Exploring More
• Search the OTN web site for more
Oracle-supplied packages
Package Name
Description
DBMS_JAVA
Controls the behavior of the Java Virtual Machine used to
run Java stored procedures
DBMS_METADATA
Retrieves information about database objects
DBMS_RANDOM
Random number generator
DBMS_SESSION
Allows access to session options directly from PL/SQL
DBMS_UTILITY
Contains a miscellaneous group of programs ranging from
capabilities to assist in procedure management to
reporting error information
DBMS_XMLGEN
Converts data from an SQL query into XML
UTL_HTTP
Accesses Web pages
UTL_INADDR
Retrieves Internet site host name or IP address
Summary
• Oracle-supplied packages are pre-built
packages to address common
processing needs
• DBMS_PIPE allows communication
between sessions
• DBMS_ALERT enables event
notification
• UTL_SMTP simplifies e-mail generation
Summary
• UTL_HTTP enables HTML source
retrieval
• UTL_TCP enables TCP/IP
communications
• DBMS_OUTPUT allows data display
• UTL_FILE enables reading and writing
to text files
• DBMS_LOB manages LOBs
Summary
• DBMS_JOB provides job scheduling
capabilities
• DBMS_DDL enables the COMPILE and
ANALYZE commands to be processed
within PL/SQL