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Open a port on Fedora

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Since MySQL Workbench 6.0 isn’t available for Fedora, Version 20, I’m having my students install it on their local Windows and Mac OS X operating systems. You can configure the /etc/sysconfig/iptables file to enable port 3306 after installing MySQL on Fedora.

You can open a port by using the firewall-config utility (easy way) or by adding the following line to the /etc/sysconfig/iptables file (Fedora’s instructions on editing iptables [hard way]). The file won’t exist initially, but you can create it by running the following command as the root superuser or sudoer:

shell> service iptables save

You you can run the following commands as the root superuser, which saves the line in the iptables file:

shell> iptables -A INPUT -m conntrack --ctstate NEW -m tcp -p tcp --dport 3306 -j ACCEPT
shell> iptables-save

After making the change to the /etc/iptables file you can change the firewall by running the following command as the root superuser:

shell> service iptables restart

Just make sure you don’t inadvertently start both iptables and ip6tables as services. You can check that only one is running by using the following commands:

shell> service iptables status
shell> service ip6tables status

MySQL Workbench Configuration

MySQL Workbench Home Page

  1. The first thing you need to do is click on the + symbol in the circle to the right of the MySQL Connections text label. It launches the Setup New Connection dialog.

Setup New Connection

  1. The second thing you need to do is enter a Connection Name, Hostname, Port, and Username. Then, click the Test Connection button.

Connect to MySQL Server

  1. The Test Connection button launches the Connect to MySQL Server dialog. Enter the password for the student user (or whatever user you’re interested in), and then click the OK button.

Connection Parameter Acknowledgment

  1. When the credentials in the Connect to MySQL Server dialog work, you see the following confirmation dialog message. Click the OK button to continue and you’ll see a new VMWare Fedora Instance connection icon.

MySQL Workbench Home Page

  1. Click the VMWare Fedora Instance connection to start a new connection.

Connect to MySQL Server

  1. The VMWare Fedora Instance button launches the Connect to MySQL Server dialog. Like you did when configuring the connection, enter the password for the student user (or whatever user you’re interested in), and then click the OK button. It launches an interactive panel that lets you run, edit, or save the SQL script file.

MySQL Workbench

  1. Type the following two lines in the Query1 panel (at least if you have a studentdb database:

    USE studentdb;
    SELECT DATABASE();

Written by maclochlainn

January 18th, 2014 at 11:51 pm

Fedora Install of MySQL

with 16 comments

I built a new image on VMWare Fusion for my class, which required installing MySQL 5.6 on Fedora, Version 20. If you don’t know how to add your user to the sudoers list, you should check this older and recently updated blog post.

  1. Download the MySQL Yum Repository and launch the downloaded RPM.
  1. Install MySQL on Fedora, Version 20, which you can find with the following command:
shell> rpm -qa | grep mysql
mysql-community-release-fc20-5.noarch

The fc20-5 changes with point releases, but assuming that you’re installing the fc20-5 release:

shell> sudo yum localinstall mysql-community-release-fc20-5.noarch.rpm
  1. Install MySQL on Fedora with the following command:
shell> sudo yum install mysql-server
  1. Start the MySQL service on Fedora with the following command:
shell> sudo service mysqld start
  1. Secure the MySQL installation with the following command:
shell> mysql_secure_installation
  1. Set the MySQL Service to start with the Fedora operating system with the following command (not chkconfig):
shell> sudo systemctl enable mysqld.service

It sets the following two links:

ln -s '/usr/lib/systemd/system/mysqld.service' '/etc/systemd/system/mysql.service'
ln -s '/usr/lib/systemd/system/mysqld.service' '/etc/systemd/system/multi-user.target.wants/mysqld.service'

Restart the Fedora operating system to effect the changes.

  1. Reset the MySQL configuration file to enable external connections through Port 3306 with the following changes to the my:

Remark out the socket line, like this:

#socket=/var/lib/mysql/mysql.sock

Add the bind-address and port lines below after you know the actual IP address of the server to the my.cnf file in the /etc directory.

You substitute the actual IP address for the nnn.nnn.nnn.nnn on the bind_address line with the actual IP address returned by the ifconfig command, like this:

shell> ifconfig

Then, add these two lines to the my.cnf file.

bind-address=nnn.nnn.nnn.nnn
port=3306

It’s actually easier to use localhost.localdomain than an IP address when you use DHCP, like:

bind-address=localhost.localdomain
port=3306

If you plan to connect from a host system, like Windows or Mac OS X, to a virtual Linux environment using DHCP, change localhost.localdomain to 0.0.0.0:

bind-address=0.0.0.0
port=3306
  1. Restart the mysqld service with the following syntax:
shell> sudo service mysqld restart

You can check whether MySQL is listening on Port 3306 with this syntax:

shell> sudo netstat –anp | grep 3306

It displays:

tcp        0      0 127.0.0.1:3306          0.0.0.0:*               LISTEN      1311/mysqld

Go to this page if you want to install MySQL Workbench.

Written by maclochlainn

January 7th, 2014 at 11:04 pm

Posted in Fedora,Linux,MySQL,VMWare

Tagged with , ,

Excel PowerPivot & DAX

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I’ve worked with every release of Microsoft Excel, and I know it takes effort to keep up to date with certain releases. Clearly, the Data Analysis eXpression (DAX) Language introduced in Excel 2010 went unnoticed by many, which was sad. DAX is truly a powerful extension to the analytical and modeling approaches in Microsoft Excel.

GoldenGateBridge2013MediumI’d like to recommend Microsoft Excel 2013 Building Data Models with PowerPivot to those who haven’t learned how to use DAX in Excel 2010, 2011, or 2013. DAX works with tables but if you don’t use tables, I guess you can skip DAX because you must have infinite time to produce marginal analytical outcomes (tongue in cheek humor). However, if you’re like most folks, you want a book to get you up-to-speed quickly, and that’s what this book will do for you.

Just one caveat if you’re using an Oracle or MySQL database, use the prepackaged analytic functions before you download the data set. You should always pre-select data before applying analytics in Excel. Remember the more refined the data model you start with the easier it is to structure analytical tools to leverage the data model. While DAX is powerful, it doesn’t replace the speed and query optimized behaviors of effective Oracle or MySQL queries.

MySQL Synonym?

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Somebody asked how to create a SYNONYM in MySQL, which is interesting because MySQL doesn’t support synonyms. I thought the prior entry explained how to do it, but here’s a new post. However, you can create a view in one database that relies on a table in another database.

The following SQL statements create two databases and grant appropriate privileges to the student as the root superuser:

/* Create two databases. */
CREATE DATABASE seussdb;
CREATE DATABASE appdb;
 
/* Grant privileges to a student user. */
GRANT ALL ON seussdb.* TO student;
GRANT ALL ON appdb.* TO student;

Log out from the root superuser and reconnect as the student user. Then, the following code connects to the seuss database and create a hat table; and inserts two rows into the hat table:

/* Use the appdb database. */
USE seussdb;
 
/* Create a hat table. */
CREATE TABLE hat
( hat_id    INT UNSIGNED PRIMARY KEY AUTO_INCREMENT
, hat_text  VARCHAR(20));
 
/* Insert two rows into the hat table. */
INSERT INTO hat (hat_text) VALUES ('Thing 1');
INSERT INTO hat (hat_text) VALUES ('Thing 2');

The following code connects to the application database and creates a hat view; and then the code inserts one additional row into the hat table:

/* Connect to the application database. */
USE appdb;
 
/* Create a hat view. */
CREATE VIEW hat AS
  SELECT * FROM seussdb.hat;
 
/* Query the contents of the view, or seuss.hat table. */
SELECT * FROM hat;
 
/* Insert a new row into the hat table. */
INSERT INTO hat (hat_text) VALUES ('Thing 3');
 
/* Query the contents of the view, after insert to the view. */
SELECT * FROM hat;

The results will be the following:

+--------+----------+
| hat_id | hat_text |
+--------+----------+
|      1 | Thing 1  |
|      2 | Thing 2  |
|      3 | Thing 3  |
+--------+----------+

I hope this answers the question on how to mimic the Oracle database’s synonyms. The appdb.hat view acts as a synonym to the seuss.hat table.

Written by maclochlainn

November 24th, 2013 at 11:10 pm

Posted in MySQL,Oracle,sql

Tagged with ,

Site Blocked in Russia?

with 11 comments

This is either too funny :-) or too sad. :-(RussianBlock

An acquaintance sent me this image from a cyber cafe or hotel in Russia. It says that my blog site is prohibited and violates Russian law, and that they’re blocking my site in accordance with the Russian Federal Law of 27.07.2006 No. 149-FZ.

All I can say is, “Wow!” I didn’t know that stuff about writing programs, web pages, and solving generic database and operating system problems was so sensitive. For that matter, I didn’t know what I post would interest any government. I half wonder whether my friend’s pulling my leg.

As I reflect on it, could it be that Oracle post on how to write an encrypted object type? or, how with proper OS credentials how you reset MySQL’s root password? or, how to verify a socket in Perl? Nah, it’s probably the one on how to set a static IP in Windows – that’s truly sensitive stuff. 😉

Does anybody who reads the blog have any clue about what would drive the Russian government to block a technology blog site like mine? My serious guess is that there is somebody who hosts with the same provider who’s done something tacky.

Written by maclochlainn

July 14th, 2013 at 8:13 pm

SQL Like Comparisons

with 4 comments

SQL tidbits are always valuable and highly searched for by newbies (as opposed to reading the SQL documentation). Sometimes we seasoned SQL developers take for granted little things like when a single- or multiple-character wildcard comparison works. It seems we know what newbies don’t. That you need a wildcard comparison operator not simply and equality comparison operator.

The question posed to me was, “Why doesn’t my wildcard comparison work?” Here’s a simplified example of their question.

SELECT 'Valid' AS "Test"
FROM    dual
WHERE  'Treat' = 'Tre_t'
OR     'Treet' = 'Tre_t';

Naturally, the answer is that the equality operator compares the strings based on their exact match (character sensitively in Oracle and character insensitively in MySQL). It needs to be rewritten by replacing the equals (=) comparison operator with the LIKE comparison operator. The following query does that:

SELECT 'Valid' AS "Test"
FROM    dual
WHERE  'Treat' LIKE 'Tre_t'
OR     'Treet' LIKE 'Tre_t'

The same behavior exists for the multiple-character wildcard (%). I hope this helps those looking for this answer.

Written by maclochlainn

July 13th, 2013 at 1:12 pm

Oracle OpenWorld 2013

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I registered yesterday for Oracle OpenWorld 2013, and I’ll look forward to seeing friends there. Having worked in the Oracle 12c beta for a year, I’ll be interested in the presentations. Also, hearing more about Java 7 at JavaOne. On the downside, I’m missing MySQL Connect this year.

Cloud computing offers many possibilities, and container and pluggable databases are a great solution. We’ve two new acronyms with the Oracle 12c release. A containerized database is a CDB, and a pluggable database is a PDB. I’m looking forward to seeing more about the provisioning of PDBs during the conference. If you’re new to the changes, check out CDBs and PDBs in Chapter 17 in the Oracle 12c Concepts manual.

A couple of my favorite new features are Identity and Invisible Columns. If you’re unfamiliar with the new features for application development, let me recommend this Oracle White Paper. Also, for reference I’ve covered identity and invisible columns thoroughly in the Oracle Database 12c PL/SQL Programming book, which will be available in December.

Missing the MySQL Connect 2013 Bus

Unfortunately, travel budgets preclude me attending MySQL Connect 2013 this year (alas, I’ll miss the bus). :-( It was hard because I’d like to see what’s up with MySQL (since I was a closet MySQL user at Oracle before they acquired it). Anyway, if you’re there, make sure you check out MySQL Workbench 6 for me. Also, I’d like to thank Dave Stokes for the AWESOME review he wrote on Amazon.com for my MySQL Workbench: Data Modeling & Development book. Maybe, I’ll get to go to MySQL Connect 2014 next year.

Written by maclochlainn

July 13th, 2013 at 11:34 am

MySQL Book in Chinese

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MySQL_JohnSinOne of my old students and lab assistants stopped by to show his fiancée the BYU-Idaho campus. It was a long trip since he lives in Macao, China.

He kindly brought me a copy of my Oracle Database 11g and MySQL 5.6 Developer Handbook in simplified Chinese. He’s holding it in the photo.

That makes three books translated into Chinese, which made my day. It’ll be interesting to see if the new MySQL Workbench: Data Modeling & Development book gets translated into Chinese too. Oddly, I never hear about this from the publisher first.

The cover emphasized only the Dolphin, not the Oracle logo material. It made me wonder, how many MySQL users there might be in China. If anybody from China catches the post, it would be great to hear about the MySQL Community in China.

Likewise, if anybody in China catches the post and reads the book, please let me know if you liked it. 😉 Naturally, let me know if you found any problems with it too. By the way, I keep an errata for the book here.

Written by maclochlainn

May 23rd, 2013 at 9:58 pm

Posted in LAMP,MySQL,Oracle

Tagged with ,

Zend 6 & Timezones

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Just went through all my PHP testing against a fresh instance of Oracle with Zend Server Community Edition 6, and found these warnings, guess that’s pretty clean for the Oracle part of the installation. I didn’t notice it before because generally I do most of my PHP development against a MySQL database. I should have been configuring the php.ini file routinely, as qualified in this PHP forum discussion.

Warning: oci_set_client_info(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in C:\Program Files (x86)\Zend\Apache2\htdocs\Oracle\Db.php on line 47
Warning: oci_set_module_name(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in C:\Program Files (x86)\Zend\Apache2\htdocs\Oracle\Db.php on line 48
Warning: oci_set_action(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in C:\Program Files (x86)\Zend\Apache2\htdocs\Oracle\Db.php on line 69

Turns out Zend 6 doesn’t automatically set the [Date] elements in the php.ini file, which is required for the oci_set_client_info(), oci_set_module_name(), and oci_set_action() functions of the OCI. You can find the php.ini file in the C:\Program Files (x86)\Zend\ZendServer\etc folder on Windows:

[Date]
; Defines the default timezone used by the date functions
; http://php.net/date.timezone
;date.timezone =
 
; http://php.net/date.default-latitude
;date.default_latitude = 31.7667
 
; http://php.net/date.default-longitude
;date.default_longitude = 35.2333
 
; http://php.net/date.sunrise-zenith
;date.sunrise_zenith = 90.583333
 
; http://php.net/date.sunset-zenith
;date.sunset_zenith = 90.583333

You can find the values for date.timezone here. Update the date.timezone as follows:

date.timezone = America/Denver

Then, reboot the Zend Server, and it fixes the warning messages.

Written by maclochlainn

May 23rd, 2013 at 11:21 am

MySQL Triggers with Logging

with one comment

Somebody asked why you can’t implement MySQL triggers that write information when you want to stop the DML statement, like autonomous procedures in Oracle. The question was a surprise but I didn’t find anything on it, so here’s how you can do it. This is more or less like an autonomous process by leveraging both the InnoDB and MyISAM engine’s behaviors. This post leverages an earlier explanation of MySQL Triggers.

  1. First you create a MyISAM table, which is a persistent store that auto commits when you’re other InnoDB tables can be transactionally dependent. Here’s a simple MyISAM logger table.
CREATE TABLE logger
( logger_id         INT UNSIGNED AUTO_INCREMENT PRIMARY KEY
, logger_event      VARCHAR(50)
, logger_table      VARCHAR(50)
, logger_instring   VARCHAR(100)
, logger_outstring  VARCHAR(100)
, created_by        INT UNSIGNED
, creation_date     DATE
, last_updated_by   INT UNSIGNED
, last_update_date  DATE) ENGINE=MyISAM;
  1. Next, you create an on-insert trigger that changes an input but doesn’t stop the transaction. It also writes to the logger MyISAM table in the scope of the transaction.
CREATE TRIGGER contact_insert
BEFORE INSERT ON contact
FOR EACH ROW
BEGIN
 
  /* Check if last name contains a white space. */
  IF new.last_name REGEXP '^.* .*$' THEN
 
    /* Insert into an MyISAM table, which auto commits in the scope
       of a transaction. */
    INSERT INTO logger
    VALUES ( null
           ,'insert'
           ,'contact'
           , new.last_name
           , REPLACE(new.last_name,' ','-')
           , new.created_by
           , new.creation_date
           , new.last_updated_by
           , new.last_update_date );
 
    /* Replace the name for the INSERT INTO the CONTACT table. */
    SET new.last_name := REPLACE(new.last_name,' ','-');
  END IF;
END;
$$

  1. Next, you create an on-update trigger that changes an update while aborting the transaction. It also writes to the logger MyISAM table because its outside the InnoDB scope of a transaction and auto committed on insert.
CREATE TRIGGER contact_update
BEFORE UPDATE ON contact
FOR EACH ROW
BEGIN
 
  /* Check if last name contains a white space. */
  IF new.last_name REGEXP '^.* .*$' THEN
 
    /* Insert into an MyISAM table, which auto commits in the scope
       of a transaction. */
    INSERT INTO logger
    VALUES ( null
           ,'update'
           ,'contact'
           , new.last_name
           , null           
           , old.created_by
           , old.creation_date
           , new.last_updated_by
           , new.last_update_date );
 
    /* Throw an exception to force the business user to see they
       can't update a last name with a white space. */
    SIGNAL SQLSTATE '42000';
  END IF;
END;
$$

  1. Next, you create a test case with an INSERT and UPDATE statement that meets the condition of the triggers.
/* Insert a row meeting the trigger condition. */
INSERT INTO contact VALUES
( null, 1001, 1003,'Catherine', null,'Zeta Jones', 1001, UTC_DATE(), 1001, UTC_DATE());
 
/* Update a row meeting the trigger condition. */
UPDATE contact
SET    last_name = 'Zeta Jones'
,      last_updated_by = 1003
,      last_update_date = UTC_DATE()
WHERE  last_name = 'Zeta-Jones';

  1. Last, query the logger table. You have a record inserted for both the allowed behavior and the aborted behavior. This means you have the ability to capture material that should never be inserted or updated into a table and who did it by leveraging the who-audit columns of the table.
SELECT * FROM logger;

It returns:

+-----------+--------------+--------------+-----------------+------------------+------------+---------------+-----------------+------------------+
| logger_id | logger_event | logger_table | logger_instring | logger_outstring | created_by | creation_date | last_updated_by | last_update_date |
+-----------+--------------+--------------+-----------------+------------------+------------+---------------+-----------------+------------------+
|         1 | insert       | contact      | Zeta Jones      | Zeta-Jones       |       1001 | 2013-04-26    |            1001 | 2013-04-26       |
|         2 | update       | contact      | Zeta Jones      | NULL             |       1001 | 2013-04-26    |            1003 | 2013-04-26       |
+-----------+--------------+--------------+-----------------+------------------+------------+---------------+-----------------+------------------+
2 rows in set (0.00 sec)

This effectively delivers in MySQL the equivalent of an autonomous transaction in Oracle. The result from the non-critical trigger records the before and after value, while the results from the critical update trigger only record the before values because the event is aborted by raising an error in the trigger. As always, I hope this helps somebody looking for a solution.

Written by maclochlainn

April 25th, 2013 at 11:01 pm