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 …

As an example for my class on the usefulness of Common Table Expressions (CTEs), I created three examples with Python. They extend an exercise in Chapter 9 on subqueries from Learning SQL by Alan Beaulieu. All of the examples work with the sakila sample database.

These bullets describe the examples:

1. Uses local variables and a range for loop and if statement that uses the variables to evaluate and add an element to the derived table (or query result set) from MySQL.
2. Uses a CTE with substitution variables from the Python program, which eliminates the need to evaluate and add an element to the query result set because the query does that.
3. Uses a table to hold the variables necessary to evaluate and add the element to the query result set.

This is the first Python program:

# Import the library.
import sys
import …

RDS(Relational Database Service) comes under “Database” services of AWS(Amazon Web Services) Cloud. In this article, we will see how to create an RDS MySql Instance, provision and terminate it.

With the CentOS project switching its focus to CentOS Stream, one of the alternatives that aim to function as a downstream build (building and releasing packages after they’re released by Red Hat) is Rocky Linux. This how-to shows how to install Percona Server for MySQL 8.0 on the Rocky Linux distribution.

You can get the information on the distribution release version by checking the /etc/redhat-release file:

[root@rocky ~]# cat /etc/redhat-release
Rocky Linux release 8.4 (Green Obsidian)

Installing and Setting up the Percona Server for MySQL 8.0  Repository

…

Sometimes life is too surreal. Like when somebody says, “How do you get title case in an Oracle database?” That’s when you know three things about the individual, while suppressing laughter. They’re not very experienced with SQL, likely lazy, and don’t read the documentation.

I had a little fun with somebody today by taking them down a small rat-hole. “Oh, gosh … ” I said, “… let’s write a function for that.” Here’s the joke function, like:

CREATE OR REPLACE
FUNCTION title_case
( string VARCHAR2 ) RETURN VARCHAR2 IS
BEGIN
  /* Change upper case to title case. */
  RETURN UPPER(SUBSTR(string,1,1)) || LOWER(SUBSTR(string,2,LENGTH(string)));
END title_case;
/

Then, we tested it with a query from the pseudo dual table:

SELECT title_case('incredible') AS "Proper Name" FROM dual;

It returned:

Proper Name
----------
Incredible

Then, I said “Oh, that’s not his …

My students liked the MySQL Transaction post but wanted one that showed how an external web application would interact with MySQL in the scope of a transaction. So, I put a little PHP function together that write across two related tables in the context of a transaction. It uses mysqli (MySQL Improved Extension) to connect PHP to the MySQL database.

The function is barebones and uses the oldest approach of hidden inputs to maintain context between rendered forms using an HTML POST method. The hidden inputs are preceded with “h_” and snake case is used for variable names.

The function only writes to two tables. It writes to the member table and when that completes successfully to the contact table. The function:

• Submits credentials from a file and raises an error when they don’t work.
• Initializes a …

There are many ways to test and edit files. A lot of developers only use their favorite Integrated Developer Environment (IDE) but I find testing script files within the scope of a pipelined set of scripts much faster.

The ability to edit a script from within the MySQL Command-Line Interface (CLI) or MySQL Shell would be nice but unfortunately, doesn’t exist. You can always subshell to edit a file or list files in the present working directory, like:

mysql> \! vi task.sql

I prefer to test at the OS level while leveraging the up-arrow key for command history. Here’s my quick edit and test script technique from your present working directory:

1. Assume you create a task.sql test file, like:

   SELECT user() AS "Current User"\G
   

2. You can edit with vi or emac and test the script interactively from the present working directory.
   …

The idea of ACID transactions are a basic feature of SQL’s individual Data Manipulation Language (DML) commands, like the INSERT, UPDATE, and DELETE statements. Transactions across two or more tables are a natural extension of ACID compliance features provided by DML commands. However, they require a structured programming approach, like a store procedure or like API implemented in an imperative language.

Surprisingly, transaction management wasn’t covered well in Alan Beaulieu’s Learning SQL because he only provided pseudo code logic. While I thought troubleshoot some broken MySQL SQL/PSM logic would be a good learning experience for students, it wasn’t. So, I wrote this sample code to show how to achieve an all or nothing transaction across four tables.

The code for this example on transaction management lets you perform the important tasks necessary to effect transaction …

Monitoring your RDS instances is very important, and the same applies to other resources. In this article, we will create a simple alarm for an RDS MySQL instance which will check for free storage space on the instance.

While you can download MySQL as a DMG package, a number of users would prefer to install it as a Docker instance. You won’t find the macOS downloads on the same web site as other downloads. You can use the following macOS download site.

After installing Docker on your macOS, you can pull a copy of the current MySQL Server with the following command:

docker pull mysql/mysql-server

You should create a mysql directory inside your ~/Documents directory with this command:

mkdir ~/Documents/mysql

Then, you should use the cd command to change into the ~/Documents/mysql directory and run this command:

pwd

It should return the following directory: …