This was principally written for my SQL students but I thought it might be useful to others. SQL calculation are performed row-by-row in the SELECT-list. In its simplest form without even touching a table, you can add two literal numbers like this:

SELECT 2 + 2 AS result;

It will display the result of the addition to the column alias result as a derived table, or the following result:

+--------+
| result |
+--------+
|      4 |
+--------+
1 row in set (0.00 sec)

Unfortunately, the use of literal values as shown above doesn’t really let you see how the calculation is made row-by-row because it only returns one row. You can rewrite the two literal values into one variable by using a Common Table Expressions (CTEs). The CTE creates an struct tuple with only one x element. Another way to describe what the CTE does would say, it creates a derived table named struct with a single …

It’s very difficult explaining to students new to relational databases how SQL works. There are many parts that seem intuitive and then there are others that confuse and confound.

For beginners, the idea that a SQL statement is simply a text string that you must dispatch to a SQL statement processing engine is new. That’s because they use an Integrated Development Environment (IDE) that hides, or abstracts the complexity, of how SQL executes.

I start my core SQL class by demonstrating how to run a text literal query without a FROM clause in MySQL Workbench, like this:

SELECT 'Hello World!' AS "Output";

After writing the query, I highlight everything except the semicolon and click the lightening bolt that dispatches the static string to the SQL statement engine. They see this result:

Then, I launch a mysql Monitor session and write the query with a semicolon to dispatch the SQL …

In 2021, I wrote a MySQL example for my class on the usefulness of Common Table Expressions (CTEs). When discussing the original post, I would comment on how you could extend the last example to build a parametric reporting table.

Somebody finally asked for a concrete example. So, this explains how to build a sample MySQL parametric query by leveraging a filter cross join and tests the parameter use with a Python script.

You can build this in any database you prefer but I used a studentdb database with the sakila sample database installed. I’ve granted privileges to both databases to the student user. The following SQL is required for the example:

-- Conditionally drop the levels table.
DROP TABLE IF EXISTS levels;
 
-- Create the levels list.
CREATE TABLE levels
( level_id       int unsigned primary key auto_increment
, …

Working with my students to create an Ubuntu virtual environment for Python development with the MySQL database. After completing the general provisioning covered in this older post, I’d recommend you create a python symbolic link before installing the MySQL-Python driver.

sudo ln -s /usr/bin/python3 /usr/bin/python

You install the Python development driver with the following:

sudo apt-get -y install python3-mysql.connector

Create a python_connect.py file to test your Python deployment’s ability to connect to the MySQL database:

#!/usr/bin/python

# Import the library.
import mysql.connector
from mysql.connector import errorcode
 
try:
  # Open connection.
  cnx = mysql.connector.connect(user='student', password='student',
                                host='localhost', …

Here’s a quick catalog for my students of PowerShell, JavaScript, and Python examples connecting to MySQL:

• MySQL Powershell Connection with .Net Library Example
• MySQL Powershell Connection with ODBC DSN Example
• MySQL Powershell with CSV File Write Example
• MySQL Powershell with Dialog for Dynamic Connection Inputs
• MySQL Node.js Introduction without Bind …

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 …

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 …

I’m always updating VMs, and I was gratified to notice that there’s a Fedora arm64 ISO. If you’re interested in it, you can download the Live Workstation from here or the Fedora Server from here.

Unfortunately, I only have macOS running on i7 and i9 Intel Processors. It would be great to hear back how it goes for somebody one of the new Apple M1 chip.

I typically install the workstation version because it meets my needs to run MySQL and other native Linux development tools. However, the server version is also available. Fedora is a wonderful option, as a small footprint for testing things on my MacBookPro.

In 2009, I showed an example of how to use the MySQL LOAD DATA INFILE command. Last year, I updated the details to reset the secure_file-priv privilege to use the LOAD DATA INFILE command, but you can avoid that approach with a simple Python 3 program like the one in this example. You also can use MySQL Shell’s new parallel table import feature, introduced in 8.0.17, as noted in a comment on this blog post.

The example requires creating an avenger table, avenger.csv file, a readWriteData.py Python script, run the readWriteData.py Python script, and a query that validates the insertion of the avenger.csv file’s data into the avenger table. The complete code in five steps using the sakila demonstration database:

• Creating the …

When I went over my example of using the WITH clause to solve how to use a series of literal values in data sets, some students got it right away and some didn’t. The original post showed how to solve a problem where one value in the data set is returned in the SELECT-list and two values are used as the minimum and maximum values with a BETWEEN operator. It used three approaches with literal values:

• A list of Python dictionaries that require you to filter the return set from the database through a range loop and if statement that mimics a SQL BETWEEN operator.
• A WITH clause that accepts the literals as bind variables to filter the query results inside the query.
• A table design that holds the literals values that an analyst might use for reporting.

It was the last example that required elaboration. I explained you might build a web form that uses a table, and the table could allow a …