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Fedora PostgreSQL Install

without comments

Somebody asked how to put PostgreSQL on my Fedora image with Oracle Database 11g and MySQL. It’s fairly simple. You can check for the current download at yum.postgresql.org and then download it like this as the root user:

yum localinstall http://yum.postgresql.org/9.3/fedora/fedora-20-x86_64/pgdg-fedora93-9.3-1.noarch.rpm

You should see the following output when the download is successful, don’t forget to type y to complete the download:

Loaded plugins: langpacks, refresh-packagekit
pgdg-fedora93-9.3-1.noarch.rpm                              | 5.1 kB  00:00     
Examining /var/tmp/yum-root-2EPf_J/pgdg-fedora93-9.3-1.noarch.rpm: pgdg-fedora93-9.3-1.noarch
Marking /var/tmp/yum-root-2EPf_J/pgdg-fedora93-9.3-1.noarch.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package pgdg-fedora93.noarch 0:9.3-1 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package           Arch       Version     Repository                       Size
================================================================================
Installing:
 pgdg-fedora93     noarch     9.3-1       /pgdg-fedora93-9.3-1.noarch     2.1 k
 
Transaction Summary
================================================================================
Install  1 Package
 
Total size: 2.1 k
Installed size: 2.1 k
Is this ok [y/d/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : pgdg-fedora93-9.3-1.noarch                                   1/1 
  Verifying  : pgdg-fedora93-9.3-1.noarch                                   1/1 
 
Installed:
  pgdg-fedora93.noarch 0:9.3-1                                                  
 
Complete!

After downloading the packages, you install with the following command:

yum install postgresql93-server

You should see the following output when the installation is successful, don’t forget to type y to complete the installation:

Loaded plugins: langpacks, refresh-packagekit
pgdg93                                                      | 3.6 kB  00:00     
(1/2): pgdg93/20/x86_64/group_gz                            |  332 B  00:00     
(2/2): pgdg93/20/x86_64/primary_db                          |  84 kB  00:00     
Resolving Dependencies
--> Running transaction check
---> Package postgresql93-server.x86_64 0:9.3.5-1PGDG.f20 will be installed
--> Processing Dependency: postgresql93-libs(x86-64) = 9.3.5-1PGDG.f20 for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64
--> Processing Dependency: postgresql93(x86-64) = 9.3.5-1PGDG.f20 for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64
--> Processing Dependency: postgresql93 = 9.3.5-1PGDG.f20 for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64
--> Processing Dependency: libpq.so.5()(64bit) for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64
--> Running transaction check
---> Package postgresql93.x86_64 0:9.3.5-1PGDG.f20 will be installed
---> Package postgresql93-libs.x86_64 0:9.3.5-1PGDG.f20 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package                  Arch        Version                 Repository   Size
================================================================================
Installing:
 postgresql93-server      x86_64      9.3.5-1PGDG.f20         pgdg93      3.6 M
Installing for dependencies:
 postgresql93             x86_64      9.3.5-1PGDG.f20         pgdg93      1.0 M
 postgresql93-libs        x86_64      9.3.5-1PGDG.f20         pgdg93      203 k
 
Transaction Summary
================================================================================
Install  1 Package (+2 Dependent packages)
 
Total download size: 4.8 M
Installed size: 22 M
Is this ok [y/d/N]: y
Downloading packages:
(1/3): postgresql93-libs-9.3.5-1PGDG.f20.x86_64.rpm         | 203 kB  00:00     
(2/3): postgresql93-9.3.5-1PGDG.f20.x86_64.rpm              | 1.0 MB  00:01     
(3/3): postgresql93-server-9.3.5-1PGDG.f20.x86_64.rpm       | 3.6 MB  00:02     
--------------------------------------------------------------------------------
Total                                              1.6 MB/s | 4.8 MB  00:02     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : postgresql93-libs-9.3.5-1PGDG.f20.x86_64                     1/3 
  Installing : postgresql93-9.3.5-1PGDG.f20.x86_64                          2/3 
  Installing : postgresql93-server-9.3.5-1PGDG.f20.x86_64                   3/3 
  Verifying  : postgresql93-server-9.3.5-1PGDG.f20.x86_64                   1/3 
  Verifying  : postgresql93-9.3.5-1PGDG.f20.x86_64                          2/3 
  Verifying  : postgresql93-libs-9.3.5-1PGDG.f20.x86_64                     3/3 
 
Installed:
  postgresql93-server.x86_64 0:9.3.5-1PGDG.f20                                  
 
Dependency Installed:
  postgresql93.x86_64 0:9.3.5-1PGDG.f20                                         
  postgresql93-libs.x86_64 0:9.3.5-1PGDG.f20                                    
 
Complete!

You can confirm the installation with the following command:

rpm -qa | grep postgres

It returns:

postgresql93-9.3.5-1PGDG.f20.x86_64
postgresql93-server-9.3.5-1PGDG.f20.x86_64
postgresql93-libs-9.3.5-1PGDG.f20.x86_64

You’ve now installed PostgreSQL. Hope this helps those timid about adding new software.

Written by maclochlainn

September 24th, 2014 at 2:43 am

MySQL Image Architecture

with 14 comments

The LinkedIn MySQL DB Development group posed a questions on how to handle images. Naturally, the argument always goes: Should images be deployed in the database or the file system? I believe they should be stored in the database because the cost and time associated is too high with regard to managing files, a file naming schema, and backing up the file system discretely from the database.

Since there’s a significant difference between the backup of transactional data and image data, they should be placed in different databases. The imagedb database is where you would place the images and large text descriptions, as shown in the MySQL Workbench ERD:

imagedb ERD

The imagedb ERD splits the foreign key references back to the system_user table, which contains the individual user credentials. The system_user table serves as the Access Control List (ACL) for the application.

Until I get a chance to write the code for this model, you can refer to the generic PHP/MySQL solution from several years back (its code source was last tested with PHP 5.3). As always, I hope this helps.

Written by maclochlainn

February 23rd, 2014 at 2:02 am

MySQL Book in Chinese

without comments

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

with one comment

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

Common Lookup Tables 2

with 2 comments

Last October I posted an example and description of a common_lookup table. It was intended to show how common_lookup tables support drop down selections in web forms. However, it wasn’t adequate to show how they work with existing data, and the function only supported fresh queries.

This post goes to the next level, and shows how to use foreign keys to preselect values for display in web forms. It also rewrites the prior function so that it supports querying existing data and inserting new data.

Let’s start with data stored in join between two tables – the member and contact tables. The internal lookup uses the customers name from the contact table to find the membership account information in the member table.

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SELECT   m.account_number
,        m.member_type         -- A fk to common_lookup table.
,        m.credit_card_number
,        m.credit_card_type    -- A fk to common_lookup table.
,        c.first_name
,        c.middle_name
,        c.last_name
,        c.contact_type        -- A fk to common_lookup table.
FROM     member m INNER JOIN contact c
ON       m.member_id = c.member_id
WHERE    c.first_name = 'Harry'
AND      c.middle_name = 'James'
AND      c.last_name = 'Potter'\G

It returns the results on the left, while a set of joins against the common_lookup table returns the results on the right (both use the \G in SQL Monitor to display the data vertically).

CommonLookupQueryResults01CommonLookupQueryResults01b

The member_type, credit_card_type, and contact_type columns in the data set on the left hold foreign key values. They’re copies of values found in the primary key column of the common_lookup table. You have the option of using these values to connect the data through a join or through function calls. A join requires three copies of the common_lookup table and yields the data displayed on the right above. The query to get the meaningful business information from the common_lookup table is:

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SELECT   m.account_number
,        cl1.common_lookup_meaning
,        m.credit_card_number
,        cl2.common_lookup_meaning
,        c.first_name
,        c.middle_name
,        c.last_name
,        cl3.common_lookup_meaning
FROM     member m INNER JOIN contact c
ON       m.member_id = c.member_id INNER JOIN common_lookup cl1
ON       cl1.common_lookup_id = m.member_type INNER JOIN common_lookup cl2
ON       cl2.common_lookup_id = m.credit_card_type INNER JOIN common_lookup cl3
ON       cl3.common_lookup_id = c.contact_type
WHERE    c.first_name = 'Harry'
AND      c.middle_name = 'James'
AND      c.last_name = 'Potter'\G

The data returned from any query is symmetrical, which means all columns return the same number of rows. The results of the preceding query are the business results. Although, they’re not what you’d want to display in a web form that presents the ability to change values, like the member, credit card, or contact types. You need to get that information by using the foreign key as a parameter to a function call, and in this case three function calls. One for each of the foreign keys from the original query results. The result is an asymmetric collection of data would look like the following conceptually with Lily Luna Potter as the customer (note the green row is the symmetrical return set from the preceding query):

AsymmetricalQueryData

The f(x) represents a generic function call where the x substitutes for the foreign key value as a lookup key to the primary key value of the common_lookup table. The function in this case is a query that returns a two column list. One column holds the primary key value of the (common_lookup_id) and the other holds the customer facing description (from the common_lookup_meaning column).

These steps describe the process:

  1. Use the natural key (the user name) to find the data in the contact table.
  2. Use the member_id foreign key column in the contact table to link to the same name column primary key in the member table by joining the two rows.
  3. Use the foreign keys in the new row (combining columns from the contact and member tables) as call parameters to a PHP function that returns all possible foreign key values and their business descriptions in a web form.

The vertical choices displayed above map to OPTION tag elements of an HTML SELECT tag. The blue highlighted value contains an instruction, Select Type, in the display of an HTML OPTION tag, and it holds a null as the value of the VALUE attribute for the OPTION tag. The other displayed rows are the possible values. The green highlighted value is the currently selected value and the yellow highlighted values are alternate possibilities for an end-user to select. The logic for that process is in the PHP get_common_lookup function below.

Having discussed the structure of the data and problem, we’ll present the result in a dynamically constructed web form below. The display form shows a member account with customer information.

CommonLookupQueryResults02

You should note that the primary and foreign keys aren’t displayed because they’re irrelevant to the business process. Primary and foreign keys only serve to support relationships when we use surrogate keys as the primary key of a table. Only the meaningful information from the common_lookup table are displayed in the preceding form. Behind the web form, the primary and foreign key values are critical to maintaining anomaly free table data.

Each of the drop downs contains the full selection of possibilities from the common_lookup table, and an end-user could choose a new value by clicking on any of the drop down fields. For example, the following displays the selection of a type of credit card:

CommonLookupQueryResults03

The user can click on the drop down, and then navigate from the selection to a new selection. Assuming we don’t change anything, submitting the form should transmit the foreign key column values. The following shows that’s exactly what it does:

CommonLookupQueryResults04

As you can see from the screen shot it works easily. Below is the PHP code for a MySQL credentials file and the get_lookup function. The function lets you find an existing value or returns a set of unique values for you to choose from.

You should rename the following credentials.php file as MySQLCredentials.inc for it to work in the file below it.

Assuming you’ve implemented the credentials.php file as the MySQLCredentials.inc file, you can now implement the following file. The get_common_lookup function returns a <SELECT> tag with a list embedded of <OPTION> tags with values; one <OPTION> tag is selected when the foreign key matches a valid primary key value in the common_lookup table; and no <OPTION> tag is selected when the foreign key doesn’t match a a valid primary key value in the common_lookup table. The last possibility means a user must choose a new valid value for the foreign key column when the foreign key column is constrained as a mandatory or not null column.

The code for the web form is a bit more complex, as shown below. It contains three separate calls to the modified get_common_lookup function (on lines 104, 111, and 126). Each call to the get_common_lookup function selects the list of possible values and highlights the value associated with the foreign key value.

Here’s the web form code. You should note that it only returns a single row of data from the query by using a natural key from the contact table.

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<html>
<header>
<title>Select Option Sample</title>
<style type="text/css">
  /* Class tag element styles. */
  .box {border:1px solid;padding:0px;width:392px;background-color:silver;}
  .bottomBox {border-left:1px solid;border-right:1px solid;border-bottom:1px solid;padding:5px;width:380px;background-color:silver;}
  .middleBox {border:1px solid;padding:5px;width:380px;background-color:silver;}
  .topBox {border-left:1px solid;border-right:1px solid;border-top:1px solid;padding:5px;width:380px;background-color:silver;}
  .button {margin:5px;background-color:lightblue;font-weight:bold;align:right;}
  .clear {clear:left;}
  .dropDown {min-width:50px;display:block;float:left;text-align:left;color:black;}
  .formDownLabel {width:90px;display:block;float:left;margin:5px;text-align:right;vertical-align:bottom;color:black;}
  .formAcrossLabel {width:80px;display:block;float:left;padding-bottom:0px;margin:5px 5px 0px;text-align:left;vertical-align:bottom;font-style:italic;font-size:90%;color:black;}
  .formInput {min-width:150px;margin:5px;text-align:left;}
  .formShortInput {width:80px;margin:5px;text-align:left;}
  .title1 {margin-left:0px;font-weight:bold;font-style:italic;font-size:125%;color:black;}
  .title2 {margin-left:5px;font-weight:bold;font-style:italic;font-size:105%;color:black;}
</style>
</header>
<body>
<?php
 
  // Include libraries.
  include_once("MySQLCredentials.inc");
  include_once("library.inc");
 
  // Define a HTML page string.
  $out = '';
 
  // Declare input variables.
  $first_name = (isset($_GET['first_name'])) ? $_GET['first_name'] : $first_name = "Harry";
  $middle_name = (isset($_GET['middle_name'])) ? $_GET['middle_name'] : $middle_name = "James";
  $last_name = (isset($_GET['last_name'])) ? $_GET['last_name'] : $last_name = "Potter";
 
  // Declare output variables.
  $member_account_number = null;
  $credit_card_number = null;
 
  // Declare lookup input and output (initialized as nulls to suppress warnings) variables.  
  $member_table = 'member';
  $member_type = 'member_type';
  $member_type_id = null;
  $credit_card_type = 'credit_card_type';
  $credit_card_type_id = null;
  $contact_table = 'contact';
  $contact_type = 'contact_type';
  $contact_type_id = null;
 
  // Assign credentials to connection.
  $mysqli = new mysqli(HOSTNAME, USERNAME, PASSWORD, DATABASE);
 
  // Check for connection error and print message.
  if ($mysqli->connect_errno) {
    print $mysqli->connect_error."<br />";
    print "Connection not established ...<br />";
  }
  else {
    // Initial statement.
    $stmt = $mysqli->stmt_init();
 
    // Declare a static query.
    $sql = "SELECT   m.account_number\n"
         . ",        m.member_type\n"
         . ",        m.credit_card_number\n"
         . ",        m.credit_card_type\n"
         . ",        c.first_name\n"
         . ",        c.middle_name\n"
         . ",        c.last_name\n"
         . ",        c.contact_type\n"
         . "FROM     member m INNER JOIN contact c\n"
         . "ON       m.member_id = c.member_id\n"
         . "WHERE    c.first_name = ?\n"
         . "AND      c.middle_name = ?\n"
         . "AND      c.last_name = ?\n";
 
    // Prepare statement.
    if ($stmt->prepare($sql)) {
      $stmt->bind_param("sss",$first_name,$middle_name,$last_name); } 
 
    // Attempt query and exit with failure before processing.
    if (!$stmt->execute()) {
 
      // Print failure to resolve query message.
      print $mysqli->error."<br />";
      print "Failed to resolve query ...<br />";
    }
    else {   
      // This query only returns one row, and an empty block follows the while logic.
      $stmt->bind_result($member_account_number, $member_type_id, $credit_card_number, $credit_card_type_id, $first_name, $middle_name, $last_name, $contact_type_id);
      while ($stmt->fetch()) {}
    }
  }
 
  // Print the query form.
  $out .= '<form method="post" name="myForm" action="submitItemType.php">';
  $out .= '<label class="title1">Membership Account Information</label><br />';
  $out .= '<div class="box">';
  $out .= '<div class="topBox">';
  $out .= '<label class="formDownLabel">Account #</label><input class="formInput" type="text" value="'.$member_account_number.'" />';
  $out .= '<select name="member_type" size="1" onChange="change(this.form.member_type)">';
 
  // Get dynamic membership type lookup string fragment.
  $out .= get_common_lookup($member_table, $member_type, $member_type_id);
 
  $out .= '</select><br />';
  $out .= '<label class="formDownLabel">Credit Card #</label><input class="formInput" type="text" value="'.$credit_card_number.'" />';
  $out .= '<select name="credit_card_type" size="1" onChange="change(this.form.credit_card_type)">';
 
  // Get dynamic credit card type lookup string fragment.
  $out .= get_common_lookup($member_table, $credit_card_type, $credit_card_type_id);
 
  // Print the closing HTML table tag.
  $out .= '</select><br />';
  $out .= '</div>';
  $out .= '<div class="middleBox">';
  $out .= '<label class="formDownLabel">&nbsp;</label>';
  $out .= '<label class="formAcrossLabel">First Name</label><label class="formAcrossLabel">Middle Name</label><label class="formAcrossLabel">Last Name</label><br class="clear" />';
  $out .= '<label class="formDownLabel">Customer</label><input class="formShortInput" type="text" value="'.$first_name.'" />';
  $out .= '<input class="formShortInput" type="text" value="'.$middle_name.'" />';
  $out .= '<input class="formShortInput" type="text" value="'.$last_name.'" /><br />';
  $out .= '<label class="formDownLabel">Type</label>';
  $out .= '<select style="margin:5px" name="contact_type" size="1" onChange="change(this.form.contact_type)">';
 
  // Get dynamic membership type lookup string fragment.
  $out .= get_common_lookup($contact_table, $contact_type, $contact_type_id);
 
  $out .= '</select><br />';
  $out .= '</div>';
  $out .= '<div class="bottomBox">';
  $out .= '<input class="button" style="margin-left:300px" name="submit" type="submit" value="Submit">';
  $out .= '</div>';
  $out .= '</form>';
  $out .= '</body>';
  $out .= '</html>';
 
  print $out;
?>
</body>
</html>

The submit button simply runs another web page that prints the actual values for the drop down selections. Here’s the code to print that:

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<html>
<head>
</head>
<body>
<?php
  // Print the surrogate key values for the common_lookup_id column.
  print "MEMBER_TYPE -> [".$_POST['member_type']."]<br />";
  print "CREDIT_CARD_TYPE -> [".$_POST['credit_card_type']."]<br />";
  print "CONTACT_TYPE -> [".$_POST['contact_type']."]<br />";
?>
</body>
</html>

I hope this helps those who are interested in sorting how to implement a common_lookup table.

Written by maclochlainn

February 1st, 2013 at 1:47 am

MySQL Workbench Scripts

with 2 comments

It’s always interesting when somebody asks why they got an error message, and especially sweet when you’re working on something related that lets you answer the question. They were using MySQL Workbench and wanted to know why they couldn’t open a SQL script file by clicking on the Scripting menu option.

As I explained to the individual who asked, you should always click the Edit SQL Script link in the SQL Development section of the MySQL Workbench home page to work on SQL scripts. The Scripting menu option supports Python and Lua plug-ins development and scripts.

They did the following initially, which led down the rabbit warren and left them stumped because they don’t know anything about Python or Lua. This is provided to those who choose to experiment with this advanced feature of MySQL Workbench.

That presents you with a chooser dialog and it lets you pick any type of file. (You may wonder, as I did, why they didn’t restrict it to .py and .lua file extensions, which would preclude opening a .sql file. I actually logged an enhancement request to see if the development team may agree with me.) You get the following message when you choose something other than a Python or Lua script. You can click on any of the reduced size screen shots to enlarge them and make them readable.

As you may note, the dialog says the activity is unsupported by provides no cancellation button. Click the OK button and the unsupported file is loaded into a tab that is useless. All you can do is click to close the tab and dismiss the window.

After you dismiss (by clicking the x) the non-editable .sql file, you need to click on the Open Script file icon shown below.

This chooser really should open where the default is for the MySQL Workbench application script files but it doesn’t. It opens in the last accessed directory. You need to navigate to where your Python or Lua scripts are stored, which is the following directory on Windows:

C:\Users\<user_name>\AppData\Roaming\MySQL\Workbench\scripts

Please note that on a Windows system you can’t chose this directory option because it’s protected. You must enter the navigation bar and type it. Then, you should see any scripts that you saved from within MySQL Workbench.

The ReadFile.py below contains a rather simplistic and static program that reads a file and prints it to console (it’s small and fits in the screen). Obviously, it dispenses with a bunch to keep it small but check a Python website or book for the right way to manage a try block and handle exceptions.

Here’s the ReadFile.py file shown in the preceding and next screen shots. For those new to Python, watch out because tabs aren’t equivalent to spaces. I made a change in the script below to display the trailing semicolon because one of my students asked about it.

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# -*- coding: utf-8 -*-
# MySQL Workbench Python script
# ReadFile.py
# Written in MySQL Workbench 5.2.41
 
import os
f = open("c:\\Data\\MySQL\\query.sql",'rU')
while True:
    line = f.readline()
    # Parse string to avoid reading line return.
    if not line[len(line) - 1:len(line)] == ";":
      print(line[0:len(line) - 1])
    else:
      print(line)
    if not line:
        break

Life’s funny, and you can never please everyone. The latest question, “Why did I choose to use substrings when suppressing line returns from the print() function is easier?” Simple answer because the approach differs between Python 2.7 and 3.0 and I didn’t want this post to have a lot of Python nuance.

Python 2.7 (compatible with MySQL Workbench 5.2):

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import os
f = open("c:\\Data\\MySQL\\query.sql",'rU')
while True:
    line = f.readline()
    # Suppress line return.
    print(line),
    if not line:
        print
        break

Python 3.0 (not-compatible with MySQL Workbench 5.2)

You should take note that both version require a print statement on line #8. Line #6 above shows that Python 2.7 uses a comma to suppress the line return, and below line #6 shows Python 3 requires you set end equal to an empty string. Line #8 below also has a set of empty parentheses, which works in Python 3.x but not in Python 2.7. Python 2.7 would print the parentheses unless you put an empty string inside of them, like a print('') statement.

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import os
f = open("c:\\Data\\MySQL\\query.sql",'rU')
while True:
    line = f.readline()
    # Suppress line return.
    print(line, end = '')
    if not line:
        print()
        break

Hopefully, everyone concurs the parsing was simpler than explaining all these Python nuances. Although, it’s nice somebody was so curious.

If your script complies with the Python 2.7 rules (that’s what is deployed in MySQL Workbench), click the lighting bolt and your code will run and display the results. That’s shown in the last screen shot.

If you’re interesting in developing plug-ins, check this summary page or this nice example of executing a query to text. Although, rumor has it that certain features may mature over the next year …

Naturally, I hope this helps those experimenting but personally it’s a cool advanced feature of the MySQL Workbench.

Written by maclochlainn

August 18th, 2012 at 4:57 pm

PHP/MySQL Query

without comments

Somebody wanted an example of how to handle column values using PHP to query a MySQL database. While I thought there were enough examples out there, they couldn’t find one that was code complete.

Well, here’s one that works using a static query. If you want to use a prepared statement, check this earlier post.

<html>
<header>
<title>Static Query Object Sample</title>
<style type="text/css">
  /* HTML element styles. */
  table {background:white;border-style:solid;border-width:3px;border-color:black;border-collapse:collapse;}
  th {text-align:center;font-style:bold;background:lightgray;border:solid 1px gray;}
  td {border:solid 1px gray;}
 
  /* Class tag element styles. */
  .ID {min-width:50px;text-align:right;}
  .Label {min-width:200px;text-align:left;}
</style>
</header>
<body>
<?php
  // Assign credentials to connection.
  $mysqli = new mysqli("localhost", "student", "student", "studentdb");
 
  // Check for connection error and print message.
  if ($mysqli->connect_errno) {
    print $mysqli->connect_error."<br />";
    print "Connection not established ...<br />";
  }
  else {
 
    // Declare a static query.
    $query = "SELECT au.system_user_id, au.system_user_name FROM system_user au" ;
 
    // Loop through a result set until completed.  
    do {
 
      // Attempt query and exit with failure before processing.
      if (!$stmt = $mysqli->query($query)) {
 
        // Print failure to resolve query message.
        print $mysqli->error."<br />";
        print "Failed to resolve query ...<br />";
      }     
      else {
 
        // Print the opening HTML table tag.
        print '<table><tr><th class="ID">ID</th><th class="Label">User Role Name</th></tr>';
 
        // Fetch a row for processing.
        while( $row = $stmt->fetch_row() ) {
 
          // Print the opening HTML row tag.
          print "<tr>";
 
          // Loop through the row's columns.
          for ($i = 0;$i < $mysqli->field_count;$i++) {
            // Handle column one differently.
            if ($i == 0)
              print '<td class="ID">'.$row[$i]."</td>";
            else
              print '<td class="Label">'.$row[$i]."</td>";
          }
          // Print the closing HTML row tag.
          print "</tr>"; 
        }
      }
    } while( $mysqli->next_result());
 
  // Print the closing HTML table tag.
  print "</table>"; 
 
  // Release connection resource.
  $mysqli->close(); }
?>
</script>
</body>
</html>

It prints the following image:

While you shouldn’t embed CSS, I’ve done it to keep this as simple as possible. You can also use the procedural approach to the MySQLi library, like this:

<html>
<header>
<title>Static Query Procedural Sample</title>
<style type="text/css">
  /* HTML element styles. */
  table {background:white;border-style:solid;border-width:3px;border-color:black;border-collapse:collapse;}
  th {text-align:center;font-style:bold;background:lightgray;border:solid 1px gray;}
  td {border:solid 1px gray;}
 
  /* Class tag element styles. */
  .ID {min-width:50px;text-align:right;}
  .Label {min-width:200px;text-align:left;}
</style>
</header>
<body>
<?php
  // Assign credentials to connection.
  $mysqli = mysqli_connect("localhost", "student", "student", "studentdb");
 
  // Check for connection error and print message.
  if (mysqli_connect_errno()) {
    print mysqli_connect_error()."<br />";
    print "Connection not established ...<br />";
  }
  else {
 
    // Initialize a statement in the scope of the connection.
    $stmt = mysqli_stmt_init($mysqli);
 
    // Declare a static query.
    $query = "SELECT au.system_user_id, au.system_user_name FROM system_user au" ;
 
    // Loop through a result set until completed.  
    do { 
 
      // Attempt query and exit with failure before processing.
      if (!$stmt = mysqli_query($mysqli,$query)) {
 
        // Print failure to resolve query message.
        print mysqli_error($stmt)."<br />";
        print "Failed to resolve query ...<br />";
      }     
      else {
 
        // Print the opening HTML table tag.
        print '<table><tr><th class="ID">ID</th><th class="Label">User Role Name</th></tr>';
 
        // Fetch a row for processing.
        while( $row = mysqli_fetch_row($stmt) ) {
 
          // Print the opening HTML row tag.
          print "<tr>";
 
          // Loop through the row's columns.
          for ($i = 0;$i < mysqli_field_count($mysqli);$i++) {
            // Handle column one differently.
            if ($i == 0)
              print '<td class="ID">'.$row[$i]."</td>";
            else
              print '<td class="Label">'.$row[$i]."</td>";
          }
          // Print the closing HTML row tag.
          print "</tr>"; 
        }
      }
    } while( mysqli_next_result($mysqli));
 
    // Print the closing HTML table tag.
    print "</table>"; 
 
    // Free system resources.
    mysqli_stmt_free_result($stmt);
 
    // Release connection resource.
    mysqli_close($mysqli); 
  }
?>
</script>
</body>
</html>

It produces the same output as the object oriented approach with one exception the title of the web page.

Hope this helps some folks.

Written by maclochlainn

July 14th, 2012 at 11:59 pm

Posted in LAMP,MAMP,MySQL,PHP

Tagged with , ,

Implicit Commit Functions?

without comments

Somebody asked about the possibility of putting DML statements inside MySQL stored functions. DML statements like the INSERT, UPDATE, and DELETE. When I said, “Yes, you can put DML statements inside functions.” They showed me the error they encountered, which is only raised at compilation when you put an explicit COMMIT statement or a Data Definition Language (DDL) statement (CREATE, ALTER, DROP, or RENAME) inside a MySQL function. The actual error message displayed is:

ERROR 1422 (HY000): Explicit OR implicit commit IS NOT allowed IN stored FUNCTION OR TRIGGER.

While an explicit COMMIT is obvious when placed inside a function, the implicit COMMIT statement isn’t obvious unless you know a DDL statement generates one. This means you can’t include any DDL statement inside a stored function.

The following example shows how a DDL statement creates an immediate implicit COMMIT. It requires two sessions and Transaction Control Language (TCL) statements.

In session one, create a table, start a transaction scope, and insert one row into the table:

-- Create a table.
CREATE TABLE message
( message_id    INT UNSIGNED PRIMARY KEY AUTO_INCREMENT
, message_text  VARCHAR(20));
 
-- Start a transaction context.
BEGIN WORK;
 
-- Insert a row into the MESSAGE table.
INSERT INTO message (message_text) VALUES ('Implicit Commit?');

In session two, the empty set is displayed when you query the MESSAGE table. Returning to session one, add a new column to the MESSAGE table with this statement:

ALTER TABLE message ADD (sent DATETIME);

The ALTER statement automatically makes current any pending data changes, effectively committing the record from session one. You can return to the second session and query the table you get the following results:

+------------+------------------+------+
| message_id | message_text     | sent |
+------------+------------------+------+
|          1 | Implicit Commit? | NULL |
+------------+------------------+------+

When you embed DML statements inside functions, they rely on automatic commit behaviors or an external transaction scope. This function compiles and returns 1 when successful and 0 when unsuccessful, which effectively controls all error conditions within the function:

CREATE FUNCTION modifies_data ( pv_message  CHAR(20) ) RETURNS INT
MODIFIES SQL DATA
BEGIN
  /* Declare Boolean-like variables as FALSE. */
  DECLARE lv_return_value INT DEFAULT FALSE;
  DECLARE lv_error_value INT DEFAULT FALSE;
 
  /* Declare a generic exit handler to reset error control variable to true. */
  DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET lv_error_value := TRUE;   
 
  /* Insert statement with auto commit enabled. */
  INSERT INTO message (message_text) VALUES (pv_message);
 
  /* True unless the CONTINUE HANDLER disables the error control variable. */ 
  IF lv_error_value = FALSE THEN
    SET lv_return_value := TRUE;
  END IF;
 
  /* Return local variable. */
  RETURN lv_return_value;
END;
$$

With auto commit enabled, any call to the function in a query writes a row to the table. If you start a transaction and in the scope of the transaction test the function in one session and query the table in another you’ll see that transaction control can be managed outside the function. You can also manage the transaction control inside a stored procedure, which holds all the TCL commands. An example follows:

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CREATE PROCEDURE test_modifies_data ( pv_message  CHAR(20) )
MODIFIES SQL DATA
BEGIN
  /* Declare a control variable that manages transaction
     success or failure. */
  DECLARE lv_success_value  INT DEFAULT FALSE;
 
  /* Start a transaction context. */
  START TRANSACTION;
 
  /* Set a SAVEPOINT in the transaction context. */
  SAVEPOINT before_transaction;
 
  /* Call the function. */
  SET lv_success_value := modifies_data(pv_message);
 
  /* Check the status of the control variable, and commit
     or rollback the transaction. */
  IF lv_success_value = TRUE THEN
    COMMIT;
  ELSE
    ROLLBACK TO before_transaction;
  END IF;
 
END;
$$

Test the two with the following call to the procedure:

CALL test_modifies_data('Agent Coulson');

Answers my question and I hope it helps others.

Written by maclochlainn

June 5th, 2012 at 1:24 am

WebSockets Introduction

with 2 comments

The topic of WebSockets came up today, and it seems a good idea to qualify WebSockets in the blog beyond simply pointing folks to Kaazing. HTML5’s WebSockets are a great fix for the half-duplex world of AJAX. They certainly have the potential to be more scalable than current Comet solutions, and present a real-time communication alternative. The latest draft of The WebSocket API was published earlier this month.

If you’re new to WebSockets, you may want to review Peter Lubbers’ PowerPoint presentation from the International Conference on Java Technology, 2010 (or the updated version he provided via a comment to this post). That is probably shorter than watching the multiple parts posted in 10-minute segments on YouTube.

More or less the PDF file of the presentation covers how HTTP is half-duplex not full duplex, and why it doesn’t support real-time data in a browser. It points to AJAX (Asynchronous JavaScript and XML) as a programming nightmare – or more precisely a workaround to a limitation of HTTP/HTTPS. It also covers the idea of COMET programming or frameworks as complex and incomplete attempts to simulate full duplex or bi-directional communication on the web.

As Peter Lubbers qualifies, AJAX and COMET solutions don’t scale against high transaction volumes or concurrency because their header traffic overwhelms the actual data transfers. This reality occurs more or less because browsers only implement unidirectional communication through a request and acknowledgement model and send large header sequences compared to small data footprints.

Peter Lubbers presents three types of HTTP solutions in the presentation:

  • Polling involves periodic requests to the server for updated information, and it is the backbone of many Ajax applications that simulate real-time communication. The HTTP message headers involved in polling are frequently larger than the transmitted data; and while polling works well in low-message rate situations it doesn’t scale well. It also involves opening and closing many connections to the server and hence database needlessly in some cases.
  • Long Polling or asynchronous-polling requests the server to keep the connection open for a set period of time. It doesn’t solve problems with high-message rates situations of polling in general because it creates a continuous loop of immediate polls and each poll, like ordinary polling messages, sends mostly HTTP headers not data.
  • Streaming architecture opens a socket but can cause problems with proxy and firewall servers, create cross-domain issues due to browser connection limits, and periodically pose overhead to flush streams that have built up in the communication channel. Streaming solutions reduce HTTP header traffic but at a cost in overhead to the server.

Websockets are designed to fix these issues. The most interesting thing about polling, long polling, streaming, or Websockets is they require the same careful attention to how databases validate user access and serve up content. When the HTML5 standard nears completion, they’ll be a great need for database connection solutions, like Oracle’s Data Resident Connection Pooling.

By the way, here are some great video links for learning HTML5.

Written by maclochlainn

May 31st, 2012 at 11:59 pm

Fixing my.cnf on Fedora

with 5 comments

Working with a Fedora 16 VM for my students (next term) and found that the MySQL Server’s my.cnf file worked with a Linux socket as opposed to a listener port, and that several configuration options where missing from the file. Here’s the default /etc/my.cnf file after the package installation from the Red Hat site:

[mysqld]
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under different user or group,
# customize your systemd unit file for mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
 
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

Without rebuilding the log files, this seemed like the cleanest replacement for the MySQL Server my.cnf for a development instance running on Fedora 16. If you’ve other suggestions, please let me know.

[mysqld]
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under different user or group,
# customize your systemd unit file for mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd
 
# Default directory.
datadir=/var/lib/mysql
 
# The TCP/IP Port the MySQL Server listens on.
# ------------------------------------------------------------
#   Find the machine's IP address with this command run as
#   the root user and use the port number specified in the
#   my.cnf file:
#   [root@localhost ~]# netstat -an | grep 3306
# ------------------------------------------------------------
 
bind-address=nnn.nnn.nnn.nnn
port=3306
 
# The Linux Socket the MySQL Server uses when not using a listener.
# socket=/var/lib/mysql/mysql.sock
 
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
 
# The default storage engine that will be used when creating new tables.
default-storage-engine=INNODB
 
# Set the SQL mode to strict.
sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
 
# Set the maximum number of connections.
max_connections=100
 
# Set the number of open tables for all threads.
table_cache=256
 
# Set the maximum size for internal (in-memory) temporary tables.
tmp_table_size=26M
 
# Set how many threads should be kept in a cache for reuse.
thread_cache_size=8
 
# MyISAM configuration.
myisam_max_sort_file_size=100G
myisam_sort_buffer_size=52M
key_buffer_size=36M
read_rnd_buffer_size=256K
sort_buffer_size=256K
 
# InnoDB configuration.
innodb_data_home_dir=/var/lib/mysql
innodb_additional_mem_pool_size=2M
innodb_flush_log_at_trx_commit=1
innodb_log_buffer_size=1M
innodb_buffer_pool_size=25M
innodb_log_file_size=5M
innodb_thread_concurrency=8
 
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

As always, I hope this helps somebody.

Written by maclochlainn

December 7th, 2011 at 1:15 am