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Reset Oracle Password

without comments

This blog entry shows you how to reset the system password for an Oracle Database. It uses a Linux image running Oracle Database 11g Express Edition. It assumes the student user is the sudoer user.

After you sign on to the student user account, you open a Terminal session and you should see the following:

[student@localhost python]$

The oracle user account should be configured to prevent a login. So, you should use the su command or sudo command to open a terminal shell as the root user.

[student@localhost python]$ sudo sh
[sudo] password for student:

As the root user, you can login as the oracle user with the following command:

su - oracle

and, you should see the following prompt. You can see the present working directory (pwd) with the pwd command:

-bash-4.2$ pwd
/u01/app/oracle

You need to source the oracle_env.sh shell file created by the installation of the Oracle Database during the installation. You have two approaches to source the environment file, the first approach is with a dot (.), like

. /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh

or, this

source /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh

The oracle_env.sh file contains the following:

export ORACLE_HOME=/u01/app/oracle/product/11.2.0/xe
export ORACLE_SID=XE
export NLS_LANG=`$ORACLE_HOME/bin/nls_lang.sh`
export PATH=$ORACLE_HOME/bin:$PATH

Now, you can connect to the Oracle Database as the internal user with the following command:

sqlplus / as sysdba

Once connected as the internal user, you can reset the system user’s password to “cangetin” with this command:

ALTER USER system IDENTIFIED BY cangetin;

At this point, you can also stop and start the database. You stop the database with this command:

shutdown immediate

You can then start the database with this command:

startup

After setting the system user password, sign out of SQL*Plus. Then, you can type two exits to return to the student user account, like this:

-bash-4.2$ exit
logout
sh-4.2# exit
exit
[student@localhost python]$

As always, I hope this helps those who need to reset the system password when they don’t know what it was to begin with.

Written by maclochlainn

February 21st, 2017 at 3:45 pm

Oracle Diagnostic Queries

without comments

It’s always a challenge when you want to build your own Oracle SQL Tools. I was asked how you could synchronize multiple cursors into a single source. The answer is quite simple, you write an Oracle object type to represent a record structure, an Oracle list of the record structure, and a stored function to return the list of the record structure.

For this example, you create the following table_struct object type and a table_list collection type:

/* Drop the types from most to least dependent. */
DROP TYPE table_list;
DROP TYPE table_struct;
 
/* Create the record type structure. */
CREATE OR REPLACE
  TYPE table_struct IS OBJECT
  ( table_name    VARCHAR2(30)
  , column_cnt    NUMBER
  , row_cnt       NUMBER );
/
 
/* Create the collection of a record type structure. */
CREATE OR REPLACE
  TYPE table_list IS TABLE OF table_struct;
/

The following listing function now reads all table names from the user_tables view. A subordinate cursor reads the user_tab_columns view for the number of columns in a table. A Native Dynamic SQL (NDS) cursor counts the number of rows in each tables found in the .

/* Create the listing function. */
CREATE OR REPLACE
FUNCTION listing RETURN table_list IS
 
  /* Variable list. */
  lv_column_cnt  NUMBER;
  lv_row_cnt     NUMBER;
 
  /* Declare a statement variable. */
  stmt  VARCHAR2(200);
 
  /* Declare a system reference cursor variable. */
  lv_refcursor  SYS_REFCURSOR;
  lv_table_cnt  NUMBER;
 
  /* Declare an output variable.  */
  lv_list  TABLE_LIST := table_list();
 
  /* Declare a table list cursor that excludes APEX tables. */
  CURSOR c IS
    SELECT table_name
    FROM   user_tables
    WHERE  table_name NOT IN
            ('DEPT','EMP','APEX$_ACL','APEX$_WS_WEBPG_SECTIONS','APEX$_WS_ROWS'
            ,'APEX$_WS_HISTORY','APEX$_WS_NOTES','APEX$_WS_LINKS'
            ,'APEX$_WS_TAGS','APEX$_WS_FILES','APEX$_WS_WEBPG_SECTION_HISTORY'
            ,'DEMO_USERS','DEMO_CUSTOMERS','DEMO_ORDERS','DEMO_PRODUCT_INFO'
            ,'DEMO_ORDER_ITEMS','DEMO_STATES');
 
  /* Declare a column count. */
  CURSOR cnt
  ( cv_table_name  VARCHAR2 ) IS
    SELECT   table_name
    ,        COUNT(column_id) AS cnt_columns
    FROM     user_tab_columns
    WHERE    table_name = cv_table_name
    GROUP BY table_name;
 
BEGIN
  /* Read through the data set of non-environment variables. */
  FOR i IN c LOOP
 
    /* Count the columns of a table. */
    FOR j IN cnt(i.table_name) LOOP
      lv_column_cnt := j.cnt_columns;
    END LOOP;
 
    /* Declare a statement. */
    stmt := 'SELECT COUNT(*) AS column_cnt FROM '||i.table_name;
 
    /* Open the cursor and write set to collection. */
    OPEN lv_refcursor FOR stmt;
    LOOP
      FETCH lv_refcursor INTO lv_table_cnt;
      EXIT WHEN lv_refcursor%NOTFOUND; 
      lv_list.EXTEND;
      lv_list(lv_list.COUNT) := table_struct(
                                    table_name => i.table_name
                                  , column_cnt => lv_column_cnt
                                  , row_cnt    => lv_table_cnt );
    END LOOP;
  END LOOP;
 
  RETURN lv_list;
END;
/

The following query pulls the processed data set as the function’s result:

COL table_name   FORMAT A20     HEADING "Table Name"
COL column_cnt   FORMAT 9,999  HEADING "Column #"
COL row_cnt      FORMAT 9,999  HEADING "Row #"
SELECT table_name
,      column_cnt
,      row_cnt
FROM   TABLE(listing);

It returns the following result set:

Table Name	     Column #  Row #
-------------------- -------- ------
SYSTEM_USER		   11	   5
COMMON_LOOKUP		   10	  49
MEMBER			    9	  10
CONTACT 		   10	  18
ADDRESS 		   10	  18
STREET_ADDRESS		    8	  28
TELEPHONE		   11	  18
RENTAL			    8  4,694
ITEM			   14	  93
RENTAL_ITEM		    9  4,703
PRICE			   11	 558
TRANSACTION		   12  4,694
CALENDAR		    9	 300
AIRPORT 		    9	   6
ACCOUNT_LIST		    8	 200
 
15 rows selected.

As always, I hope this helps those trying to work with the Oracle database.

Written by maclochlainn

January 5th, 2017 at 7:28 pm

Install cx_Oracle for Python

without comments

This shows you how to install the cx_Oracle library for Python 2.7 on Fedora Linux. If Fedora has it on the server you can download it with the following yum command:

yum install -y cx_Oracle-5.2.1-11g-py27-1.x86_64.rpm

Currently, you’ll get the following failure because it’s not available in the Fedora repository:

Loaded plugins: langpacks, refresh-packagekit
mysql-connectors-community                                      | 2.5 kB  00:00:00     
mysql-tools-community                                           | 2.5 kB  00:00:00     
mysql56-community                                               | 2.5 kB  00:00:00     
pgdg93                                                          | 3.6 kB  00:00:00     
updates/20/x86_64/metalink                                      | 2.3 kB  00:00:00     
No package cx_Oracle-5.2.1-11g-py27-1.x86_64.rpm available.
Error: Nothing to do

You can download the cx_Oracle library from the Python web site. The cx_Oracle documentation qualifies module interfaces, objects, and connections. Assuming your Linux user’s name is student, you download the cx_Oracle library into the /home/student/Downloads directory. Then, you use the su or sudo command to become the root user.

As the root user, run the following yum command:

yum install -y ~student/Downloads/cx_Oracle-5.2.1-11g-py27-1.x86_64.rpm

You should see the following output:

Loaded plugins: langpacks, refresh-packagekit
Examining /home/student/Downloads/cx_Oracle-5.2.1-11g-py27-1.x86_64.rpm: cx_Oracle-5.2.1-1.x86_64
Marking /home/student/Downloads/cx_Oracle-5.2.1-11g-py27-1.x86_64.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package cx_Oracle.x86_64 0:5.2.1-1 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
=======================================================================================
 Package        Arch        Version      Repository                               Size
=======================================================================================
Installing:
 cx_Oracle      x86_64      5.2.1-1      /cx_Oracle-5.2.1-11g-py27-1.x86_64      717 k
 
Transaction Summary
=======================================================================================
Install  1 Package
 
Total size: 717 k
Installed size: 717 k
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : cx_Oracle-5.2.1-1.x86_64                                            1/1 
  Verifying  : cx_Oracle-5.2.1-1.x86_64                                            1/1 
 
Installed:
  cx_Oracle.x86_64 0:5.2.1-1                                                           
 
Complete!

After you install the cx_Oracle-5.2.1-1.x86_64 package, you can find the installed files with this rpm command:

rpm -ql cx_Oracle-5.2.1-1.x86_64

It lists:

/usr/lib64/python2.7/site-packages/cx_Oracle-5.2.1-py2.7.egg-info
/usr/lib64/python2.7/site-packages/cx_Oracle-5.2.1-py2.7.egg-info/PKG-INFO
/usr/lib64/python2.7/site-packages/cx_Oracle-5.2.1-py2.7.egg-info/SOURCES.txt
/usr/lib64/python2.7/site-packages/cx_Oracle-5.2.1-py2.7.egg-info/dependency_links.txt
/usr/lib64/python2.7/site-packages/cx_Oracle-5.2.1-py2.7.egg-info/top_level.txt
/usr/lib64/python2.7/site-packages/cx_Oracle.so
/usr/share/doc/cx_Oracle-5.2.1
/usr/share/doc/cx_Oracle-5.2.1/BUILD.txt
/usr/share/doc/cx_Oracle-5.2.1/README.txt
/usr/share/doc/cx_Oracle-5.2.1/samples
/usr/share/doc/cx_Oracle-5.2.1/samples/DatabaseChangeNotification.py
/usr/share/doc/cx_Oracle-5.2.1/samples/DatabaseShutdown.py
/usr/share/doc/cx_Oracle-5.2.1/samples/DatabaseStartup.py
/usr/share/doc/cx_Oracle-5.2.1/samples/ReturnLongs.py
/usr/share/doc/cx_Oracle-5.2.1/samples/ReturnUnicode.py
/usr/share/doc/cx_Oracle-5.2.1/samples/RowsAsInstance.py
/usr/share/doc/cx_Oracle-5.2.1/test
/usr/share/doc/cx_Oracle-5.2.1/test/3kArrayDMLBatchError.py
/usr/share/doc/cx_Oracle-5.2.1/test/3kNumberVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/3kStringVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/ArrayDMLBatchError.py
/usr/share/doc/cx_Oracle-5.2.1/test/BooleanVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/Connection.py
/usr/share/doc/cx_Oracle-5.2.1/test/Cursor.py
/usr/share/doc/cx_Oracle-5.2.1/test/CursorVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/DateTimeVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/IntervalVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/LobVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/LongVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/NCharVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/NumberVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/ObjectVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/SessionPool.py
/usr/share/doc/cx_Oracle-5.2.1/test/SetupTest.sql
/usr/share/doc/cx_Oracle-5.2.1/test/StringVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/TestEnv.py
/usr/share/doc/cx_Oracle-5.2.1/test/TimestampVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/test.py
/usr/share/doc/cx_Oracle-5.2.1/test/test3k.py
/usr/share/doc/cx_Oracle-5.2.1/test/test_dbapi20.py
/usr/share/doc/cx_Oracle-5.2.1/test/uArrayDMLBatchError.py
/usr/share/doc/cx_Oracle-5.2.1/test/uConnection.py
/usr/share/doc/cx_Oracle-5.2.1/test/uCursor.py
/usr/share/doc/cx_Oracle-5.2.1/test/uCursorVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uDateTimeVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uIntervalVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uLobVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uLongVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uNumberVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uObjectVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uSessionPool.py
/usr/share/doc/cx_Oracle-5.2.1/test/uStringVar.py
/usr/share/doc/cx_Oracle-5.2.1/test/uTimestampVar.py

After you installed the software, you can test whether inside Python’s IDLE environment with the import command, like this:

Python 2.7.5 (default, Apr 10 2015, 08:09:05) 
[GCC 4.8.3 20140911 (Red Hat 4.8.3-7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: libclntsh.so.11.1: cannot open shared object file: No such file or directory

This error indicates that Oracle Client software isn’t installed, which is true in this case. I only installed the Oracle Database 11g Express Edition. You need to download the Oracle Client software and install it as the root user.

You download the Oracle Client software from the Oracle web site. Assuming your Linux user’s name is student, you download the cx_Oracle library into the /home/student/Downloads directory. Then, you use the su or sudo command to become the root user.

As the root user, run the following yum command:

yum install -y ~student/Downloads/oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm

You should see the following output:

Loaded plugins: langpacks, refresh-packagekit
Examining /home/student/Downloads/oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm: oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64
Marking /home/student/Downloads/oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package oracle-instantclient11.2-basic.x86_64 0:11.2.0.4.0-1 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package
        Arch   Version
                      Repository                                           Size
================================================================================
Installing:
 oracle-instantclient11.2-basic
        x86_64 11.2.0.4.0-1
                      /oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64 179 M
 
Transaction Summary
================================================================================
Install  1 Package
 
Total size: 179 M
Installed size: 179 M
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64           1/1 
  Verifying  : oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64           1/1 
 
Installed:
  oracle-instantclient11.2-basic.x86_64 0:11.2.0.4.0-1                          
 
Complete!

You can create a Python program that checks your ability to connect to the Oracle database, like the following oracleConnection.py file:

# Import the Oracle library.
import cx_Oracle
 
try:
  # Create a connection.
  db = cx_Oracle.connect("student/student@xe")
 
  # Print a message.
  print "Connected to the  Oracle " + db.version + " database."
 
except cx_Oracle.DatabaseError, e:
  error, = e.args
  print >> sys.stderr, "Oracle-Error-Code:", error.code
  print >> sys.stderr, "Oracle-Error-Message:", error.message
 
finally:
  # Close cursor. 
  db.close()

You can run this from the Linux command line with the following syntax:

python oracleConnection.py

It should return the following string:

Connected to the Oracle 11.2.0.2.0 database.

Now, you can create a Python program that reads data from the Oracle database. The following oracleString.py file reads a string literal from the pseudo table dual:

# Import the Oracle library.
import cx_Oracle
 
try:
  # Create a connection.
  db = cx_Oracle.connect("student/student@xe")
 
  # Create a cursor.
  cursor = db.cursor()
 
  # Execute a query.
  cursor.execute("SELECT 'Hello world!' FROM dual")
 
  # Read the contents of the cursor.
  for row in cursor:
    print (row[0]) 
 
except cx_Oracle.DatabaseError, e:
  error, = e.args
  print >> sys.stderr, "Oracle-Error-Code:", error.code
  print >> sys.stderr, "Oracle-Error-Message:", error.message
 
finally:
  # Close cursor and connection. 
  cursor.close()
  db.close()

You can run this from the Linux command line with the following syntax:

python oracleString.py

It should return the following string:

Hello world!

Now, you can create a Python program that reads actual table data from the Oracle database (assuming you have a copy of my video store database). The following oracleTable.py file reads a string literal from the pseudo table dual:

# Import the Oracle library.
import cx_Oracle
 
try:
  # Create a connection.
  db = cx_Oracle.connect("student/student@xe")
 
  # Create a cursor.
  cursor = db.cursor()
 
  # Execute a query.
  cursor.execute("SELECT item_title, item_subtitle FROM item")
 
  # Read the contents of the cursor.
  for row in cursor:
    print (row[0], row[1]) 
 
except cx_Oracle.DatabaseError, e:
  error, = e.args
  print >> sys.stderr, "Oracle-Error-Code:", error.code
  print >> sys.stderr, "Oracle-Error-Message:", error.message
 
finally:
  # Close cursor and connection. 
  cursor.close()
  db.close()

You can run this from the Linux command line with the following syntax:

python oracleTable.py

It should return the following strings (only a subset of the returned values):

("Harry Potter and the Sorcer's Stone", 'Two-Disc Special Edition')
('Harry Potter and the Chamber of Secrets', 'Two-Disc Special Edition')
('Harry Potter and the Prisoner of Azkaban', 'Two-Disc Special Edition')
('Harry Potter and the Chamber of Secrets', None)
('Harry Potter and the Goblet of Fire', 'Widescreen Edition')
('Harry Potter and the Goblet of Fire', 'Two-Disc Special Edition')
('Harry Potter and the Order of the Phoenix', 'Widescreen Edition')
('The Lord of the Rings - Fellowship of the Ring', 'Widescreen Edition')
('The Lord of the Rings - Fellowship of the Ring', 'Platinum Series Special Extended Edition')
('The Lord of the Rings - Two Towers', 'Widescreen Edition')
('The Lord of the Rings - Two Towers', 'Platinum Series Special Extended Edition')
('The Lord of the Rings - The Return of the King', 'Widescreen Edition')
('The Lord of the Rings - The Return of the King', 'Platinum Series Special Extended Edition')
('Star Wars - Episode I', 'The Phantom Menace')
('Star Wars - Episode II', 'Attack of the Clones')
('Star Wars - Episode III', 'Revenge of the Sith')
('Star Wars - Episode IV', 'A New Hope')
('Star Wars - Episode V', 'The Empire Strikes Back')
('Star Wars - Episode VI', 'Return of the Jedi')

As always, I hope this helps others who want to work with Python and the Oracle database.

Written by maclochlainn

October 19th, 2016 at 1:47 am

Oracle Segment Fails

with 2 comments

The instance that I’ve built for my students in a Fedora VM is quite stable except for one feature. The feature is the hibernation process of the base operating system. Sometimes when the base operating system hibernates, it causes the Oracle shared memory segment to fail. When that happens you get the following error:

ERROR:
ORA-01034: ORACLE NOT available
ORA-27101: shared memory realm does NOT exist
Linux-x86_64 Error: 2: No such FILE OR DIRECTORY
Process ID: 0
SESSION ID: 0 Serial NUMBER: 0

I created the master sudoer account as the student user. The oracle user is configured so that you can’t log in to the Linux OS with it. To restart the instance you can do the following in a default Oracle 11g XE installation:

su - root

or, you can do this:

sudo sh

Then as the root user, you can sign on to the oracle user’s account by using the su command without a password, like:

su - oracle

As the user who installed the Oracle instance, you can connect to the database without a password after you source the environment file. The standard Oracle 11g XE environment file can be sources like this:

. /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh

Alternatively, for my students there is a .bashrc file that they can manually source. It contains the following:

# Source global definitions
if [ -f /etc/bashrc ]; then
  . /etc/bashrc
fi
 
# Uncomment the following line if you don't like systemctl's auto-paging feature:
# export SYSTEMD_PAGER=
 
# User specific aliases and functions
. /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh
 
# Wrap sqlplus with rlwrap to edit prior lines with the
# up, down, left and right keys.
sqlplus()
{
  if [ "$RLWRAP" = "0" ]; then
    sqlplus "$@"
  else
    rlwrap sqlplus "$@"
  fi
}
 
# Set vi as a command line editor.
set -o vi

You can source the oracle user’s .bashrc account, like this:

. .bashrc

After you’ve sourced the environment, you can connect as the internal user with the following syntax:

sqlplus / AS sysdba

Connected as the internal user, run these two commands in sequence:

shutdown IMMEDIATE
startup

Then, you should be able to connect as the student user or another ordinary user with the following syntax:

CONNECT student/student

Hope this helps my students and those who want to know how to restart the Oracle instance.

Written by maclochlainn

October 16th, 2016 at 10:29 pm

Oracle EBS 12.2 & Ruby

without comments

As does seem to occur from time-to-time, I’m out there in the weeds again and sorting out a solution that fits a customer’s need. They wanted to know if they could write Oracle EBS 12.2 Concurrent Manager Programs in Ruby. They don’t want to write Java.

I checked the documentation, which as is too common, didn’t answer the question. I’m sure if I downloaded the PDF and searched it for one of the languages I knew Oracle supported, I would have found the list of supported languages.

It was simply quicker to query the Oracle EBS 12.2 FND_LOOKUPS table like so:

SELECT   lookup_type
,        lookup_code
,        SUBSTR(meaning,1,30) AS meaning
FROM     fnd_lookups
WHERE    lookup_type = 'CP_EXECUTION_METHOD_CODE'
ORDER BY meaning;

It returns the list of possible types of Oracle EBS 12.2 Concurrent Manager Programs:

LOOKUP_TYPE		   LOOKUP_CODE	MEANING
-------------------------- ------------ ------------------------------
CP_EXECUTION_METHOD_CODE   X		FlexRpt
CP_EXECUTION_METHOD_CODE   F		FlexSql
CP_EXECUTION_METHOD_CODE   H		Host
CP_EXECUTION_METHOD_CODE   S		Immediate
CP_EXECUTION_METHOD_CODE   K		Java Concurrent Program
CP_EXECUTION_METHOD_CODE   J		Java Stored Procedure
CP_EXECUTION_METHOD_CODE   M		Multi Language Function
CP_EXECUTION_METHOD_CODE   P		Oracle Reports
CP_EXECUTION_METHOD_CODE   I		PL/SQL Stored Procedure
CP_EXECUTION_METHOD_CODE   E		Perl Concurrent Program
CP_EXECUTION_METHOD_CODE   B		Request Set Stage Function
CP_EXECUTION_METHOD_CODE   L		SQL*Loader
CP_EXECUTION_METHOD_CODE   Q		SQL*Plus
CP_EXECUTION_METHOD_CODE   R		SQL*Report
CP_EXECUTION_METHOD_CODE   Z		Shutdown Callback
CP_EXECUTION_METHOD_CODE   A		Spawned

That gave me some of the answer. You can’t call Ruby programs directly. However, Perl lets you use Inline::Ruby. You can use Inline:Ruby to call your Ruby programs. So, if you use Perl to wrap Ruby you don’t have to use Java.

Written by maclochlainn

August 23rd, 2016 at 11:50 am

DB_LINK w/o tnsnames.ora

without comments

A question popped up, which I thought was interesting. How can you create a DB_LINK in Oracle without the DBA changing the tnsnames.ora file? It’s actually quite easy, especially if the DBA sets the TNS address name the same as the instance’s service name or in older databases SID value.

  1. Do the following with the tnsping utility:
    tnsping mohawk

    It should return this when the server’s hostname is mohawk and domain name is techtinker.com:

    TNS Ping Utility for Linux: Version 11.2.0.2.0 - Production on 26-JUL-2016 16:55:58
     
    Copyright (c) 1997, 2011, Oracle.  All rights reserved.
     
    Used parameter files:
     
     
    Used TNSNAMES adapter to resolve the alias
    Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = mohawk.techtinker.com)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = ORCL)))
    OK (10 msec)
  1. You can now create a DB_LINK in another Oracle instance without a tnsnames.ora entry by referencing the type of server connection and service name with the following syntax (please note that you should remove extraneous white space):
    CREATE DATABASE LINK test
      CONNECT TO student IDENTIFIED BY student
      USING '(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=mohawk.techtinker.com)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=ORCL)))'

    In an older database version, you may need to refer to the SID, like this:

    CREATE DATABASE LINK test
      CONNECT TO student IDENTIFIED BY student
      USING '(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=mohawk.techtinker.com)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SID=ORCL)))'

    Then, you can query a contact table in the remote instance like this:

    SELECT COUNT(*)
    FROM   contact@test;

As always, I hope this helps somebody trying to solve a problem.

Written by maclochlainn

July 26th, 2016 at 6:15 pm

Debug PL/SQL Web Pages

without comments

What happens when you can’t get a PL/SQL Web Toolkit to work because it only prints to a web page? That’s more tedious because any dbms_output.put_line command you embed only prints to a SQL*Plus session. The answer is quite simple, you create a test case and test it inside a SQL*Plus environment.

Here’s a sample web page that fails to run successfully …

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CREATE OR REPLACE
  PROCEDURE html_table_values
  ( name_array   OWA_UTIL.VC_ARR
  , value_array  OWA_UTIL.VC_ARR ) IS
  BEGIN
    /* Print debug to SQL*Plus session. */
    FOR i IN 1..name_array.COUNT LOOP
      DBMS_OUTPUT.put_line('Value ['||name_array(i)||'='||value_array(i)||']');
    END LOOP;
 
    /* Open HTML page with the PL/SQL toolkit. */
    htp.print('<!DOCTYPE html>');
    htp.htmlopen;
    htp.headopen;
    htp.htitle('Test');
    htp.headclose;
    htp.bodyopen;
    htp.line;
    htp.print('Test');
    htp.line;
    htp.bodyclose;
    htp.htmlclose;
END;
/

You can test the program with the following anonymous block as the SYSTEM user, which is equivalent to the following URL:

http://localhost:8080/db/html_table_values?begin=1004&end=1012

The following test program lets you work:

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DECLARE
  x  OWA_UTIL.VC_ARR;
  y  OWA_UTIL.VC_ARR;
BEGIN
  /* Insert first row element. */
  x(1) := 'begin';
  y(1) := '1004';
 
  /* Insert second row element. */
  x(2) := 'end';
  y(2) := '1012';
 
  /* Call the anonymous schema's web page. */
  anonymous.html_table_values(x,y);
END;
/

It should print:

Value [begin=1004]
Value [end=1012]

I hope this helps those looking for a solution.

Written by maclochlainn

May 16th, 2016 at 5:18 pm

SQL Developer & PL/SQL

without comments

While SQL Developer installs with a dbms_output view, some organizations close it before they distribute images or virtual machine (VM) instances. This post shows you how to re-enable the Dbms Output view for SQL Developer.

SQL Developer DBMS_OUTPUT Configuration

SQLDeveloper1

  1. You need to open SQL Developer, which may look like this when the DBMS_OUTPUT view isn’t visible.

SQLDeveloper1

  1. You need to click on the View menu option in SQL Developer and choose the Dbms Output dropdown menu element.

SQLDeveloper1

  1. You should see a grayed-out Dbms Output view.

SQLDeveloper1

  1. You should type a simply “Hello World!” anonymous block program in PL/SQL, like the one shown in the drawing.

SQLDeveloper1

  1. After writing the “Hello World!” anonymous block program in PL/SQL, click the green arrow to start the statement and you will see two things. There is now a Script Output view between your console and Dbms Output views, and it should say “anonymous block completed.” Unfortunately, none of your output is displayed in the Dbms Output view because you need to enable it.

SQLDeveloper1

  1. If you hover over the Dbms Output view’s green arrow, you see the help message that describes the behavior of the green arrow. The Dbms Output green arrow lets you enable the Dbms Output view for output.

SQLDeveloper1

  1. After you click the Dbms Output view’s green arrow, you receive a Select Connection prompt for the view. Make sure you have the right user, and click the OK button to continue.

SQLDeveloper1

  1. After you create the connection for the Dbms Output stream, the view area becomes white rather than gray.

SQLDeveloper1

  1. Click the green arrow to start the statement and you will see the “Hello World!” string in the Dbms Output view.”

As always, I hope this helps those looking for a solution.

Written by maclochlainn

May 13th, 2016 at 10:55 am

Using a Sparse Index

with 2 comments

My vacation from my blog is officially over. The question that I’m answering today is: How can you pass a set of non-sequential ID values to a function and return a result set? You can solve the problem by passing an ADT (Attribute Data Type) or UDT (User Defined Type) variable into a subquery of a cursor. The subquery leverages the TABLE function to translate the ADT or UDT into SQL result set, which is equivalent to a comma-delimited list of values.

You can also solve this problem with Native Dynamic SQL (NDS). However, the person who posed the question didn’t want to use NDS to build out a variable length list of comma-delimited numbers.

You need to create three object types for this example. They are:

  • a list of numbers
  • a record structure, declared as an object type without methods
  • a list of the record structure

These are the SQL commands to create the required data types:

CREATE OR REPLACE
  TYPE list_ids IS TABLE OF NUMBER;
/
CREATE OR REPLACE
  TYPE item_struct IS OBJECT
  ( item_id       NUMBER
  , item_title    VARCHAR2(80)
  , release_date  DATE );
/
CREATE OR REPLACE
  TYPE item_struct_list IS TABLE OF item_struct;
/

Next, you create a nonsynchronous function. It takes a sparsely populated list of values that map to the surrogate key of the column, which is typically the table’s primary key column. It returns a collection of the item_struct object type. This type of function is an object-table function.

The code follows:

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CREATE OR REPLACE
  FUNCTION nonsynchronous 
  ( pv_list_ids  LIST_IDS ) RETURN item_struct_list IS
    /* Declare a record data structure list. */
    lv_struct_list  ITEM_STRUCT_LIST := item_struct_list();
 
    /* Declare a sparsely indexed list of film items. */
    CURSOR get_items
    ( cv_list_ids  LIST_IDS ) IS
      SELECT   item_id AS item_id
      ,        item_title
      ||       CASE
                 WHEN item_subtitle IS NOT NULL THEN
                   ': '|| item_subtitle
               END AS item_title
      ,        release_date AS release_date
      FROM     item
      WHERE    item_id IN (SELECT *
                           FROM   TABLE(cv_list_ids))
      ORDER BY item_id;
BEGIN
  /* Lood through the sparsely populated list of numbers. */
  FOR i IN get_items(pv_list_ids) LOOP
    lv_struct_list.EXTEND;
    lv_struct_list(lv_struct_list.COUNT) := item_struct( item_id      => i.item_id
                                                       , item_title   => i.item_title
                                                       , release_date => i.release_date );
  END LOOP;
 
  /* Return the record structure list. */
  RETURN lv_struct_list;
END;
/

The foregoing nonsynchronous function uses a nested query that transforms to a result set on lines 18 and 19. In the execution block of the program, it uses a call to the item_struct structure to capture and assign row values to an element of the lv_struct_list variable.

You can now test the nonsynchronous function with the following query:

COL item_id      FORMAT 9999  HEADING "Item|ID #"
COL item_title   FORMAT A40   HEADING "Item Title"
COL release_date FORMAT A11   HEADING "Release|Date"
SELECT   *
FROM     TABLE(nonsynchronous(list_ids(1002, 1013, 1007)));

The query returns the record set as an ordered list in the result set, like:

Item					       Release
 ID # Item Title			       Date
----- ---------------------------------------- -----------
 1002 Star Wars I: Phantom Menace	       04-MAY-99
 1007 RoboCop				       24-JUL-03
 1013 The DaVinci Code			       19-MAY-06

I hope this answers the question about how to get results sets with sparsely populated ID values.

Written by maclochlainn

May 11th, 2016 at 1:37 am

REGEXP_LIKE Behavior

with one comment

Often, the biggest problem with regular expressions is that those who use them sometimes don’t use them correctly. A great example occurs in the Oracle Database with the REGEXP_LIKE function. For example, some developer use the following to validate whether a string is a number but it only validates whether the first character is a number.

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DECLARE
  lv_input  VARCHAR2(100);
BEGIN
  /* Assign input value. */
  lv_input := '&input';
 
  /* Check for numeric string. */
  IF REGEXP_LIKE(lv_input,'[[:digit:]]') THEN
    dbms_output.put_line('It''s a number.');
  ELSE
    dbms_output.put_line('It''s a string.');
  END IF;
END;
/

When they test numbers it appears to works, it even appears to work when the test string start with number, but it fails with any string that starts with a character. That’s because the REGEXP_LIKE function on line 8 only checks the first character, but the following checks all the characters in the string.

8
  IF REGEXP_LIKE(lv_inputs(i),'[[:digit:]]{'||LENGTH(lv_inputs(i))||'}') THEN

You can also fix it with the following non-Posix solution:

8
  IF REGEXP_LIKE(lv_input,'[[0-9]]') THEN

You can add a collection to the program and use it to test single-digit, double-digit, and string with a leading integer. Save the program as test.sql and you can test three conditions with one call.

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DECLARE
  /* Declare the local collection type. */
  TYPE inputs IS TABLE OF VARCHAR2(100);
 
  /* Declare a local variable of the collection type. */
  lv_inputs  INPUTS;
BEGIN
  /* Assign the inputs to the collection variable. */
  lv_inputs := inputs('&1','&2','&3');
 
  /* Read through the collection and print whether it's an number or string. */
  FOR i IN 1..lv_inputs.COUNT LOOP
    IF REGEXP_LIKE(lv_inputs(i),'[[:digit:]]{'||LENGTH(lv_inputs(i))||',}') THEN
      dbms_output.put_line('It''s a number.');
    ELSE
      dbms_output.put_line('It''s a string.');
    END IF;
  END LOOP;
END;
/

You can run the test.sql program like this:

SQL> @test.sql 1 12 1a

It prints:

It's a number.
It's a number.
It's a string.

As always, I hope this helps those looking for a solution.

Written by maclochlainn

September 30th, 2015 at 7:23 pm