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Displaying posts with tag: MySQL Developer (reset)
AlmaLinux MySQL Workbench

AlmaLinux doesn’t natively support MySQL Workbench but these notes will help you install it. The great news is that MySQL Workbench works perfectly once you’ve installed all the dependent libraries. It’ll look like the following:

Disclaimer of sorts:

AlmaLinux is an open-source, community-driven project that intends to fill the gap left by the demise of the CentOS stable release. AlmaLinux is a 1:1 binary compatible fork of RHEL® 9 and it is built by the AlmaLinux OS Foundation as a standalone, completely free OS. The AlmaLinux OS Foundation will support future RHEL® releases by updating AlmaLinux. Ongoing development efforts are governed by the members of the community.

You can download MySQL Workbench from the following website:

https://dev.mysql.com/downloads/workbench

When you open this page, select the Red Hat Enterprise Linux 9 / Oracle Linux 9 (x86, 64-bit), RPM Package from the dropdown …

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AlmaLinux MySQL+Perl

A quick primer on Perl programs connecting to the MySQL database. It’s another set of coding examples for the AlmaLinux instance that I’m building for students. This one demonstrates basic Perl programs, connecting to MySQL, returning data sets by reference and position, dynamic queries, and input parameters to dynamic queries.

  1. Naturally, a hello.pl is a great place to start:
    #!/usr/bin/perl
    
    # Hello World program.
    print "Hello World!\n";
    

    After setting the permissions to -rwxr-xr-x. with this command:

    chmod 755 hello.pl
    

    You call it like this from the Command-Line Interface (CLI):

    ./hello.pl
    

    It prints:

    Hello World!
    
  2. Next, a connect.pl program lets us test the Perl::DBI connection to the MySQL database.
    #!/usr/bin/perl
    
    # Import libraries.
    use strict;
    use warnings;
    use v5.10;     # for …
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AlmaLinux LAMP


After installing and configuring MySQL 8.0.30, I installed the Apache Web Server, PHP and the MySQLi packages. Here are the step-by-step instructions after installing and configuring the MySQL Server and provisioning a student user and the sakila and studentdb databases (blog for those steps). After installing the major components, I completed the HTTPS configuration steps for Apache 2.

The installation steps are:

  1. Install the Apache packages as the sudoer user with this command:
    sudo dnf install -y httpd
    
  2. Enable Apache as the sudoer user with this command:
    chkconfig httpd on
    

    This returns the following completion message:

    Note: Forwarding request to 'systemctl enable httpd.service'.
    Created symlink …
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AlmaLinux MySQL+Python

After installing and configuring MySQL 8.0.30, I installed the Python connector. During that process on AlmaLinux, there were several changes since I last installed the Python’s mysql module. Here are the step-by-step instructions after installing and configuring MySQL Server (blog for those steps).

Using the MySQL Connector/Python X DevAPI Reference, you must install the pip utility before you install the library. You install the pip library as a sudoer user with the following command:

sudo yum install -y pip

Then, using the pip utility as a sudoer user install the mysql-connector-python module with the following command:

sudo pip install mysql-connector-python

Please note that this …

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MySQL on AlmaLinux

After installing AlmaLinux in a VMware VM on my MacBook Pro (Intel Chip), and updating the packages with the following command:

sudo dnf upgrade --refresh -y

MySQL was first on my installation and configuration list. Here are the commands to install and configure it on AlmaLinux.

Install the MySQL Server packages and dependents:

sudo dnf install mysql mysql-server -y

Install the MySQL service utilities with the initscripts package, using the following command:

sudo yum install -y initscripts

Start the MySQL daemon with the following command:

sudo service mysqld start

Connect and verify the root user can connect to the database. At this point, you’ve not set the root user’s password and should use the following syntax:

mysql -uroot

It should connect and display:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your …
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MySQL Workbench Keys

As I teach students how to create tables in MySQL Workbench, it’s always important to review the meaning of the checkbox keys. Then, I need to remind them that every table requires a natural key from our prior discussion on normalization. I explain that a natural key is a compound candidate key (made up of two or more column values), and that it naturally defines uniqueness for each row in a table.

Then, we discuss surrogate keys, which are typically ID column keys. I explain that surrogate keys are driven by sequences in the database. While a number of databases disclose the name of sequences, MySQL treats the sequence as an attribute of the table. In Object-Oriented Analysis and Design (OOAD), that makes the sequence a member of the table by composition rather than aggregation. Surrogate keys are also unique in the table but should never be used to determine uniqueness like the natural key. Surrogate keys are also candidate keys, like a …

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MySQL Query from JSON

One of my students asked how you could get JSON data out in tabular format. I said they should look at Øystein Grøvlen’s JSON_TABLE – Best of Both Worlds blog post from 2018. Unfortunately, the student wanted another example with the Video Store model that we use in class.

For clarity, all path definitions start with a $ followed by other selectors:

  • A period followed by a name, such as $.website
  • [N] where N is the position in a zero-indexed array
  • The .[*] wildcard evaluates all members of an object
  • The [*] wildcard evaluates all members of an array
  • The prefix and suffix wildcard, **, evaluates to all paths that begin with the named prefix and end with the named suffix

So, here’s a quick supplement to what’s already there. It assumes you created an …

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MySQL Backslashes

Yesterday, I wrote a blog post that showed you how to write a query returning a JSON structure for a 1:many relationship. The relationship was between the member and contact table. It returns one account_number from the member table and a list of first_name and last_name columns from the contact table in a JSON structure.

One of my students asked why I choose to strip the backslashes with Python, and my reply was the SQL was already complex for most blog readers. The student asked but how would you do it in SQL. OK, that’s a fair question for two reasons. First, you don’t need to do in your local programs because it’ll run faster on the server. Second, if you strip the backslashes you can insert it into a standard JSON column. This blog post will show you how to do both.

You would use three REGEXP_REPLACE function calls, like:

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MySQL JSON Tricks

Are they really tricks or simply basic techniques combined to create a solution. Before writing these mechanics for using native MySQL to create a compound JSON object, let me point out that the easiest way to get one is to use the MySQL Node.js library, as shown recently in my “Is SQL Programming” blog post.

Moving data from a relational model output to a JSON structure isn’t as simple as a delimited list of columns in a SQL query. Let’s look at it in stages based on the MySQL Server 12.18.2 Functions that create JSON values.

Here’s how you return single row as a JSON object, which is quite straightforward:

SELECT JSON_OBJECT('first_name',c.first_name,'last_name',c.last_name) AS json_result
FROM   contact c
WHERE …
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Is SQL Programming


Is SQL, or Structured Query Language, a programming language? That’s a great question! A question that many answer with emphasis: “No, SQL is not a programming language!” There are some who answer yes; and they usually qualify that answer with something like: “SQL is a programming language designed to communicate with relational databases.”

It strikes me that those saying “yes” are saying that SQL is only a collection of interface methods to read from and write to a database engine. Those saying SQL is not a programming language often qualify that a programming language must have conditional logic and iterative structures, which don’t exist in SQL.

There’s a third group that are fence sitters. They decline to say whether SQL is a programming language, but they also say individuals who only write SQL aren’t programmers. That’s a bit harsh from my perspective.

Before …

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