Each SQL dialect is different in some way, shape, form, or
fashion from the next flavor. Some dialects have this
function, while others have that function. In this post, I cover
porting over Oracle SQL to MySQL in order to count the
number of occurrences of a specific weekday found in the current
given month (at the time of writing) purely as a learning
exercise focused on MySQL DATE functions and the
WITH clause…
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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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Self-Promotion:
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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]If you use SQL on a regular basis, then you are well aware that Window Functions are powerful. They allow us to simplify queries that would otherwise be quite the mess. We can provide meaningful insight across rows of data without collapsing the results into a single value. I have written numerous blog posts on Window Functions, many here recently. I decided to make this blog post a compilation of all the Window Function posts I have written, providing a one-stop source for any readers interested in learning more about Window Functions…
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[Read more]Top n Window Function queries over a specific subset of data are common in analysis and reporting requirements. Luckily, in MySQL, there are Window functions we can use for this type of query. To be quite honest, you don’t necessarily need Window Functions. You can retrieve those top 3 (or whatever) types of results with a regular SQL query. But, since we have those powerful Window Functions, why not use them? My thoughts exactly! Besides, no one wants a spaghetti code mess of SQL to try and understand. Not to mention, Window functions are often better optimized for querying larger data sets. Continue reading and see example queries for more understanding…
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Rolling sum and average query results are possible by combining
the aggregate functions SUM() or AVG()
with the OVER() clause, making for powerful analytic
queries. I recently learned how to compute a rolling
average or sum of values by using the Windowing option
of the OVER() clause, applying the concepts to a
data set I am familiar with. I wanted to share my learning with
any readers who might be interested…
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The Window Ranking functions: ROW_NUMBER(),
RANK(), and DENSE_RANK() each
rank rows with an increasing integer value. I wrote a
previous blog post, ROW_NUMBER() Window Function – find duplicate
values, where I covered how the ROW_NUMBER()
window function can be used to target any duplicate rows, with
the use of the PARTITION BY clause in the
OVER() clause. In this post, I cover the differences
between RANK(), and DENSE_RANK() in
handling any ties according to the sorting performed by the
ORDER BY clause with regards to the assigned
increasing integer. Continue reading and see examples…
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Many times, we do not want duplicate rows or values in our SQL
tables. On the other hand, in some situations, it does not matter
if there are duplicates present. For whatever reason, suppose
duplicates have found their way into one of your tables. How can
you find them quickly and easily? The ROW_NUMBER()
Window function is a fantastic tool to use. Continue
reading and see example queries you can apply to your own tables
and find those duplicates…
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OS and DB used:
These days, I mostly program in PHP with MySQL as the database,
which is just fine by me. I have had a long-time interest in
MySQL (SQL in general), and after several steady months
of programming in PHP, I must say I have really come into the
language and developed a fondness for it. All that being said, I
still enjoy using and learning the MySQL Shell in Python mode. As
Database Developers, we often need the LAST INSERT
ID value from a previous INSERT statement on
a column that has the AUTO_INCREMENT attribute.
MySQL Shell has a get_auto_increment_value() method
we can call against a Shell object result and retrieve that
value. Continue reading and see examples of the MySQL Shell
get_auto_increment_value() method used in Python
mode…
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