I record this for posteriority without much comment.

The error message “Truncated incorrect DOUBLE value” when issued by MySQL can be a confused parser, and masks unintended barely legal syntax:

kris@localhost [kris]> select * from testtable;
+----+------+
| id | d    |
+----+------+
|  1 | eins |
|  2 | zwei |
|  3 | drei |
+----+------+
3 rows in set (0.00 sec)
 
kris@localhost [kris]> update testtable set d="vier" and id = 4 where id = 3;
ERROR 1292 (22007): Truncated incorrect DOUBLE value: 'vier'

The actual problem here is the incorrect use of and in the set-clause of the update statement when a comma was intended.

kris@localhost [kris]> update testtable set d="vier", id = 4 where id = 3;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Technically, an and is possible and legal, if you …

When using MySQL with Python, you may want to use the mysqlclient library, which is what most people do and which will work just fine. Or you are using the official MySQL 8 Connector/Python package, which will behave slightly differently, but maybe supports the unique MySQL 8 feature already that is not in mysqlclient, yet.

Your SQL may be hand-writtten, or it may be generated using SQL Alchemy, Django or some other package. If the latter is the case, it may be useful to be able to see the actual SQL string that has been sent to the database in order to facilitate interactive debugging.

Using mysqlclient

If you are using mysqlclient with Python, the class internally sends the SQL to the server in a method _query(self, q) in the Cursor class ( …

Question: how do I know that one user is waiting for a lock and another  user is burning CPU on MySQL?

i.e. how can I create active session history on MySQL like on Oracle?

Two simple cases I’m looking at

1. session waiting on lock
   1. The wait event is ” wait/io/table/sql/handler” which happens for a number of potential reasons
   2. -> I can join to information_schema views INNODB_LOCK_WAITS & INNODB_TRX but this is heavy, and I’d rather only access those after I know there is a lock waiter.
2. session burning CPU
   1. How do I know from performance schema views that the connection is active and burning CPU?
   2. It has a wait event that shows up wait/synch/mutex/sql/THD::LOCK_thd_data
   3. on Oracle to determine CPU, we just …

In keeping with my MySQL 8 user administration and security theme, I’d like to discuss the password verification-required policy introduced in MySQL 8.0.13. With this feature, it is possible to require that attempts to change an account password be verified by specifying the existing current password to be replaced.

Introduction

The password verification-required policy enables DBAs to prevent users from changing a password without proving that they know the current password. When would this happen? Such changes could occur if a user walked away from a terminal session without logging out, and a malicious user uses the open session to change the original user’s MySQL password. As you can imagine, this could have disastrous consequences:

• The original user is now unable to access MySQL until an administrator can reset the account password. 
• The malicious user can access MySQL until a password …

Oracle released MySQL 8.0.28 on January 18th with little fanfare, as part of their four times a year release cycle.  So what is included in the new release? Over the past few years, there have been some cool new features included in these ‘dot’ releases that some in the community say would have been better off being labeled as a major release. But what is in .28? Below are the more interesting changes in the database server and the shell, as there was not a whole lot changed in the other products such as router or MEM… I put my asides in italics and my views probably do not reflect the views of anyone else.

And remember, 8.0.29 is due in April.

The TL;DR

The TL;DR synopsis is that a lot of excellent work went into MySQL Server & shell 8.0.28 but the pressing question is do you really need to install it right away?  On the scale from ‘you probably should wait to upgrade’ to ‘update ASAP’ it …

KMIP (Key Management Interoperability Protocol) is an open standard developed by OASIS (Organization for Advancement of Structured Information Standards) for the encryption of stored data and cryptographic key management.

Percona Server for MySQL 8.0.27 and Percona XtraBackup 8.0.27 now include a KMIP keyring plugin to enable the exchange of cryptographic keys between a key management server and the database for encryption purposes. The procedure to use them with HashiCorp Vault Enterprise is described below.

Install Hashicorp Vault Enterprise

We will first install Hashicorp Vault Enterprise on Ubuntu Linux “Bionic” and then enable …

Supercharge your productivity in MySQL Workbench with these ‘click and paste’ SQL code snippets available for any table in a schema. Continue reading and see the ‘Staple Five‘…

Do you need to learn MySQL? Just starting and confused about how to query a table and get the data you need? I am creating premium MySQL Beginners content for this specific reason. To help those who want to learn the basics of MySQL but don’t know where to start. Learn more about the premium blog posts as I develop and release them.

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Self-Promotion:

If you enjoy the content written here, by all means, share this blog and your favorite post(s) with others who may benefit from or like it as well. Since coffee is my favorite drink, you can even buy me …

Getting a count of table or query rows in CodeIgniter 4 is quite easy using either of the Query Builder countAll() or countAllResults() functions. Continue reading to see examples of each…

Do you need to learn MySQL? Just starting and confused about how to query a table and get the data you need? I am creating premium MySQL Beginners content for this specific reason. To help those who want to learn the basics of MySQL but don’t know where to start. Learn more about the premium blog posts as I develop and release them.

Tell me more!

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In this tutorial, you’ll learn how to build a mood tracker application with Laravel 9, connect it to a PlanetScale MySQL database, make database schema changes, and deploy your database branch to production. You’ll use PlanetScale for the database, which gives you a fully managed MySQL-compatible database, unlimited scalability, a Git-like development workflow, zero downtime schema changes, and more.

Warning

This blog post is over a year old and may be out of date.

Here are some of the highlights of what you’ll create:

• A production-ready MySQL database in PlanetScale
• 2 database branches: main for production and dev for development
• 2 tables, moods and entries, to store your daily entries and mood options
• Database migrations and a seeder to run on your …

Rollback is an operation, which changes the current state of the transaction to the previous state. Undo logs are generally required if we want to roll back any of the uncommitted transactions and it plays a major role in Isolation.

For any changes made during a transaction, it must be stored priorly, because they are required if we choose to roll back the transaction.

Entries are made in undo logs when data modifications are done. If a transaction modifies data with SQL commands, It will create discrete undo logs for each operation. Once a transaction is committed MySQL is free to purge the undo logs created in that transaction. 

To know more about undo logs, you can check our previous blogs on overview to undo logs.

Usually, the Rollback process will take more time than the original operation. Because …