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Displaying posts with tag: MySQL Developer (reset)
Session Variables

In MySQL and Oracle, you set a session variable quite differently. That means you should expect there differences between setting a session variable in Postgres. This blog post lets you see how to set them in all three databases. I’m always curious what people think but I’m willing to bet that MySQL is the simplest approach. Postgres is a bit more complex because you must use a function call, but Oracle is the most complex.

The difference between MySQL and Postgres is an “@” symbol versus a current_setting() function call. Oracle is more complex because it involves the mechanics in Oracle’s sqlplus shell, SQL dialect, and PL/SQL language (required to assign a value to a variable).

MySQL

MySQL lets you declare a session variable in one step and use it one way in a SQL statement or stored procedure.

  1. You set a session variable on a single line with the following …
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mysqli Strict Standards

Six years ago I wrote a common lookup post to illustrate the effectiveness of things used throughout your applications. Now, I’m updating my student image with a more complete solution to show how to avoid update anomalies.

In the prior post, I used a while loop in PHP, like the following:

do {
      ...
} while($stmt->next_result());

Using PHP Version 7.3.8 and MySQL 8.0.16, that now raises the following error message:

Strict Standards: mysqli_stmt::next_result(): There is no next result set. Please, call mysqli_stmt_more_results()/mysqli_stmt::more_results() to check whether to call this function/method in /var/www/html/app/library.inc on line 81

You can see this type of error when you set the following parameters in your file during testing:

ini_set('display_errors',1); …
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MySQL Update in mysqli

Somebody didn’t like the MySQLi Update Query example on the tutorialspoint.com website because it use the procedure mysqli_query style. Here’s a simple example of using the object-oriented method version. More or less, instead of query it uses the more intuitive execute() method.

The update_member function contains the logic and below it is a call to the test the function. It relies on a MySQLCredentials.inc file that contains the hostname, user name, password, and database name. You can create create member table, like my example in MySQL 8, or any other table in your MySQL database.

<?php /*
||  Function Name: update_member
*/
function update_member($account_number, $member_type, …
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Python MySQL Query

Somebody asked me how to expand a prior example with the static variables so that it took arguments at the command line for the variables. This example uses Python 3 new features in the datetime package.

There’s a small trick converting the string arguments to date data types. Here’s a quick example that shows you how to convert the argument list into individual date data type variables:

#!/usr/bin/python3

# include standard modules
import sys
from datetime import datetime

# Capture argument list.
fullCmdArguments = sys.argv

# Assignable variables.
beginDate = ""
endDate = ""

# Assign argument list to variable.
argumentList = fullCmdArguments[1:]

# Enumerate through the argument list where beginDate precedes endDate as strings.
try:
  for i, s in enumerate(argumentList):
    if (i == …
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MySQL Python Connector

While building my student image on Fedora 30, I installed the MySQL PHP Connector (php-mysqlndrp) but neglected to install the Python Connector. This adds the installation and basic test of the Python Connector to the original blog post.

You use the following command with a wildcard as a privileged user. The wildcard is necessary because you need to load two libraries to support Python 2.7 and 3.7, which are installed on Fedora 30. You also need to be the root user or a user that is found in the sudoer’s list:

yum install -y mysql-connector-python*

Display detailed console log

Last metadata expiration check: 0:35:46 ago on Tue 20 Aug 2019 05:36:29 PM MDT.
Dependencies resolved. …
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Apache on Fedora 30

There was an option during the Fedora 30 Workstation installation to add the Apache Web Server, but you need to set it to start automatically. Unfortunately, there was no option to install PHP, which I thought odd because of how many web developers learn the trade first on PHP with a LAMP (Linux, Apache, MySQL, Perl/PHP/Python) stack. You see how to fix that shortcoming in this post and how to install and test PHP, mysqli, and pdo to support MySQL 8.

Before you do that make sure you install MySQL 8. You can find my prior blog post on that here.

You set Apache to start automatically, on the next boot of the operating system, with the following command:

chkconfig httpd on

It creates a symbolic link:

Created symlink /etc/systemd/system/multi-user.target.wants/httpd.service → …
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MySQL on Fedora 30

While updating my class image to Fedora 30, I noticed that it installed the Akonadi Server. The documentation on the Akonadi server lacked some straightforward documentation. It also offered a bundled set of software that limited how to approach MySQL development.

So, I removed all those packages with the following syntax:

dnf remove `rpm -qa | grep akonadi`

Display detailed console log

Dependencies resolved.
=============================================================================
 Package                          Arch    Version            Repo       Size
=============================================================================
Removing:
 akonadi-import-wizard            x86_64  19.04.2-1.fc30     @updates  2.8 M
 kf5-akonadi-calendar             x86_64  19.04.2-1.fc30     @updates  2.6 M
 kf5-akonadi-contacts             x86_64  19.04.2-1.fc30     @updates  3.3 M
 kf5-akonadi-mime …
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MySQL 5.7.* and mysqli

After installing MySQL 5.7.22 and PHP 7.1.17 on Fedora 27, you need to install the mysqli library. You need to verify if the mysqli library is installed. You can do that with the following mysqli_check.php program:


Check mysqli Install<?php if (!function_exists('mysqli_init') && !extension_loaded('mysqli')) {
    print 'mysqli not installed.'; }
  else {
    print 'mysqli installed.'; }
?>

You test preceding PHP program with the following URL in a browser:

http://localhost/mysqli_check.php

If the mysqli program isn’t installed, you can install it as follows by opening the yum interactive shell:

[root@localhost html]# yum shell
Last metadata expiration check: 1:26:46 ago on Wed 22 Aug 2018 08:05:50 PM MDT.
> remove php-mysql
No match for argument: php-mysql
Error: No packages marked for removal.
> install php-mysqlnd
> …
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MySQL on Fedora 27

While updating my class image to Fedora 27, I noticed that it installed the Akonadi Server. The documentation on the Akonadi server lacked some straightforward documentation. It also offered a bundled set of software that limited how to approach MySQL development.

So, I removed all those packages with the following syntax:

dnf remove `rpm -qa | grep akonadi`

After removing those Akonadi packages, I installed the MySQL Community Edition from the Fedora repo with this syntax:

yum install -y community-mysql*

Having installed MySQL Community Edition, I started the service with this command:

sudo service mysql start

Then, I ran the mysql_secure_installation script to secure the installation:

mysql_secure_installation

The script set the root user’s password, remove the anonymous user, disallow remote root login, and …

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Fedora LAMP Steps

I posted earlier in the year how to configure a Fedora instance to test PHP code on a local VM. However, I’ve got a few questions on how to find those posts. Here’s a consolidation with links on those steps:

  1. Go to this blog post and install the httpd and php libraries with the yum installer.
  2. In the same blog post as step 1 (you can put the sample PHP code into the /var/www/html directory for testing), connect to the yum shell and remove the php-mysql library and then install the mysqlnd library.
  3. Go to this blog …
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