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 …

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 …

While I blogged about how to setup Node.js and MySQL almost two years ago, it was interesting when a student ran into a problem. The student said they’d configured the environment but were unable to use Node.js to access MySQL.

The error is caused by this import statement:

const mysql = require('mysql') 

The student got the following error, which simply says that they hadn’t installed the Node.js package for MySQL driver.

internal/modules/cjs/loader.js:638
    throw err;
    ^

Error: Cannot find module 'mysql'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object. (/home/student/Data/cit325/oracle-s/lib/Oracle12cPLSQLCode/Introduction/query.js:4:15)
    at Module._compile …

MySQL Partitioned Tables

Learning Outcomes

• Learn about List Partitioning.
• Learn about Range Partitioning.
• Learn about Columns Partitioning.
• Learn about Hash Partitioning.
• Learn about Key Partitioning.
• Learn about Subpartitioning.

Lesson Material

MySQL supports partitioning of tables. It supports range, list, hash, and key partitioning. Range partitioning lets you partition based on column values that fall within given ranges. List partitioning lets you partition based on columns matching one of a set of discrete values. Hash partitioning lets you partition based on the return value from a user-defined expression (the result from a stored SQL/PSM function). Key partitioning performs like hash partitioning, but it lets a user select one or more columns from the …

Almost a Ripley’s Believe It or Not. An prior data science student told me that his new IT department setup a Windows component that let him connect his Excel Spreadsheets to their production MySQL database without a password. Intrigued, I asked if it was a MySQL Connector/ODBC Data Source Configuration, or DSN (Data Source Name)?

He wasn’t sure, so I asked him to connect to PowerShell and run the following command:

Get-Item -Path Registry::HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI\MySQL

It returned something like this (substituting output from one of my test systems):

    Hive: HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI


Name                           Property
----                           --------
MySQL                          Driver      : C:\Program Files\MySQL\Connector ODBC 8.0\myodbc8w.dll
                               DESCRIPTION : MySQL ODBC Connector
                               SERVER      : …

Saturday, I posted how to use Microsoft ODBC DSN to connect to MySQL. Somebody didn’t like the fact that the PowerShell program failed to write a *.csv file to disk because the program used the Write-Host command to write to the content of the query to the console.

I thought that approach was a better as an example. However, it appears that it wasn’t because not everybody knows simple redirection. The original program can transfer the console output to a file, like:

powershell .\MySQLODBC.ps1 > output.csv

So, the first thing you need to do is add a parameter list, like:

param (
  [Parameter(Mandatory)][string]$fileName
)

Anyway, it’s trivial to demonstrate how to modify the PowerShell program to write to a disk. You should also create a virtual PowerShell drive before writing the file. That’s because you can change the physical directory anytime you want with minimal changes to rest of …

This post explains and demonstrates how to install, configure, and use the MySQL’s ODBC libraries and a DSN (Data Source Name) to connect your Microsoft PowerShell programs to a locally or remotely installed MySQL database. After you’ve installed the MySQL ODBC library, use Windows search field to find the ODBC Data Sources dialog and run it as administrator.

There are four steps to setup, test, and save your ODBC Data Source Name (DSN) for MySQL. You can click on the images on the right to launch them in a more readable format or simply read the instructions.

MySQL ODBC Setup Steps

1. Click the SystemDSN tab to see he view which is …

A student wanted a better example of writing a MySQL Persistent Stored Module (PSM) that maintains transactional scope across a couple tables. Here’s the one I wrote about ten years ago to build the MySQL Video Store model. It looks I neglected to put it out there before, so here it is for reference.

-- Conditionally drop procedure if it exists.
DROP PROCEDURE IF EXISTS contact_insert;

-- Reset the delimiter so that a semicolon can be used as a statement and block terminator.
DELIMITER $$

SELECT 'CREATE PROCEDURE contact_insert' AS "Statement";
CREATE PROCEDURE contact_insert
( pv_member_type         CHAR(12)
, pv_account_number      CHAR(19)
, pv_credit_card_number  CHAR(19)
, pv_credit_card_type    CHAR(12)
, pv_first_name          CHAR(20)
, pv_middle_name         CHAR(20)
, pv_last_name           CHAR(20)
, pv_contact_type        CHAR(12)
, pv_address_type        CHAR(12)
, pv_city                CHAR(30)
, pv_state_province      CHAR(30)
, …

In MySQL, the @@sql_mode parameter should generally use ONLY_FULL_GROUP_BY. If it doesn’t include it and you don’t have the ability to change the database parameters, you can use a MySQL PSM (Persistent Stored Module), like:

Create the set_full_group_by procedure:

-- Drop procedure conditionally on whether it exists already.
DROP PROCEDURE IF EXISTS set_full_group_by;

-- Reset delimter to allow semicolons to terminate statements.
DELIMITER $$

-- Create a procedure to verify and set connection parameter.
CREATE PROCEDURE set_full_group_by()
  LANGUAGE SQL
  NOT DETERMINISTIC
  SQL SECURITY DEFINER
  COMMENT 'Set connection parameter when not set.'
BEGIN

  /* Check whether full group by is set in the connection and
     if unset, set it in the scope of the connection. */
  IF NOT EXISTS
    (SELECT NULL
     WHERE  REGEXP_LIKE(@@SQL_MODE,'ONLY_FULL_GROUP_BY'))
  THEN
    SET SQL_MODE=(SELECT CONCAT(@@sql_mode,',ONLY_FULL_GROUP_BY'));
  END IF; …

I always get interesting feedback on some posts. On my test case for discovering the STR_TO_DATE function’s behavior, the comment was tragically valid. I failed to cleanup after my test case. That was correct, and I should have dropped param table and the two procedures.

While appending the drop statements is the easiest, I thought it was an opportunity to have a bit of fun and write another procedure that will cleanup test case tables within the test_month_name procedure. Here’s sample dynamic drop_table procedure that you can use in other MySQL stored procedures:

CREATE PROCEDURE drop_table
( table_name  VARCHAR(64))
BEGIN
 
  /* Declare a local variable for the SQL statement. */
  DECLARE stmt VARCHAR(1024);
 
  /* Set a session variable with two parameter markers. */
  SET @SQL := CONCAT('DROP TABLE ',table_name);
 
  /* Check if the …