I recently published a blog post over on Medium
about the differences in 2 versions of the MySQL
COUNT() aggregate function: COUNT(*)
and COUNT(column_name or expression). I wanted to
share the post here with any readers who may be interested so
continue reading for more on this post…
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[Read more]CodeIgniter’s Query Builder ORM has class methods for nearly any kind of database access/operation you can think of. In this post, I’ll cover some of the available methods for retrieving aggregate-level query results. The examples in this post map out Query Builder method chaining to produce results you would get from a raw MySQL query. Continue reading to see more…
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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 …
[Read more]Introduction In this article, I’m going to explain how to do query profiling using the MySQL Performance Schema. The Performance Schema has been available since MySQL 5.5.3 and allows MySQL to instrument SQL queries and store their trace information in various tables that you can later inspect in order to determine why a given SQL statement is slow. On older versions of MySQL, you might have used the SHOW PROFILE command, but since this feature has been deprecated, you should now use the Performance Schema for SQL query profiling. Enabling the MySQL... Read More
The post MySQL Query Profiling Using Performance Schema appeared first on Vlad Mihalcea.
Most developers use some form of auto-incrementing integer
counter for a given database table, ensuring uniqueness
among the rows. Several of the popular SQL dialects implement
this facility. For instance, MySQL’s AUTO_INCREMENT
attribute is used to provide a unique identity for a table row.
What exactly is the behavior of AUTO_INCREMENT? Can
you explicitly use a value of your choosing for it if you need
to? How does it count? Continue reading and know the answers to
these questions and more…
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[Read more]CSV imports with MySQL Workbench, is super simple. Since CSV’s are probably the most common data interchange format, it goes without saying that importing CSV data into MySQL is a staple task for all DBA’s and Developers. Continue reading to learn how easy it is using MySQL Workbench…
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[Read more]Some believe the most important part of SQL is the ability to query data. Queries typically retrieve data by joining many tables together into useful result sets. This tutorial takes the position that visibility into the data helps those new to SQL understand how joins work. To that end, the queries use Common Tabular Expressions (CTEs) instead of tables.
Default behavior of a JOIN without a qualifying
descriptor is not simple because it may return:
CROSS JOIN (or Cartesian Product) when there
is no ON or USING subclause, or
INNER JOIN when you use an ON or
USING subclause.
The following query uses JOIN without a qualifier or an ON or USING subclause. It also uses two copies of the single CTE, which is more or less a derived table and the result of a subquery held in memory. This demonstrates the key …
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MySQL membership conditions are in the MySQL 8 Documentation.
They’re found in the 13.2.11.3 Subqueries with
ANY, IN, or SOME
section. The IN and =ANY operators both
perform equality matches with one twist. The IN
operator works with a set of values or a subquery but the
=ANY operator only works with a subquery.
I created the digits, letters, and
words tables for this example. They hold the
following values respectively:
numbers table holds the values of
1, 2, 3, and
4
letters table holds the values of
'a', 'b', 'c', and
'd'
words table holds the values of
'Captain America', 'Iron …I recently published a blog post about a portfolio project I am developing using the LAMP stack, Bootstrap 4, jQuery, and the MVC (Model-View-Controller) design pattern in core PHP. In this post, I will introduce an additional feature I integrated into the existing project.
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[Read more]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: …
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