I recently learned of some odd behavior using MySQL BETWEEN operator queries, filtering by a DATETIME column. I wrote about this over on Medium so I am sharing the post for any readers here who are interested…
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During many decision-making phases in programming code
(conditional logic), there are times execution depends on
several different factors. Multiple conditional tests
are powerful and constraining, oftentimes requiring more than one
test to be passed in order for program flow to proceed. For MySQL
(and standard SQL in general) the CASE expression is
used for IF/THEN/ELSE
conditional logic. The post, MySQL Simple CASE Expression – with
examples, covered Simple CASE queries which
are essentially equality tests. MySQL Simple CASE is
but one variant of 2, with the other being a MySQL
Searched CASE Expression. A MySQL Searched
CASE Expression can have multiple
conditional tests in each WHEN …
Programming logic is foundational in any application or piece of
software. Without it, software wouldn’t really do much of
anything. Everything happens off of choice. In the end, some
truthy or falsy value is what makes stuff work.
For IF/THEN/ELSE logic in
standard SQL, there is the CASE expression. There
are 2 variations of the CASE Expression: Simple and
Searched. In this post, I cover the Simple MySQL
CASE expression with example queries…
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Be it running reports or displaying data in some other
visualization, SQL SELECT column expressions should
be meaningful and understandable. To provide those valuable query
results, SQL Developers, use a multitude of available functions,
adjacent columns, or other means not readily apparent to
end-users. All that being said, the column names often suffer the
most as far as readability is concerned, taking on long function
call names or other combined expressions. But, as luck would be
on our side, there is an easy fix and that is aliasing columns
using the AS keyword. Although AS is
optional – in this particular context – I err on the side of
readability and use it when aliasing SELECT column
expressions.
Introduction In this article, we are going to see what a Clustered Index is and why it’s very important to understand how tables are organized when using a relational database system. B+ Tree The most common index used in a relational database system is the B+ Tree one. Like the B-Tree index, the B+ Tree is a self-balanced ordered tree data structure. Both the B-Tree and the B-Tree start from a Root node and may have Internal Nodes and Leaf Nodes. However, unlike the B-Tree, the B+ Tree stores all the keys... Read More
The post Clustered Index appeared first on Vlad Mihalcea.
Any of you who read my blog posts here regularly know I am passionate about SQL, PHP, and Back-end Development. I consider writing an integral part of my brand and growth. Continue reading and learn more about what’s on my mind lately with writing and code…
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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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…
[Read more]Sometimes clients want that the information they collected from the user should be encrypted and stored in a database. Data encryption and…
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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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[Read more]In the last post I covered some of the many reasons to migrate data from a spreadsheet to a database and now it is time to show how to do just that. Moving data from a spreadsheet into MySQL can actually be pretty simple in many cases. Now I will not mislead you by telling you that all cases are easy but there is an easy way to make this migration. And I highly recommend the following process when possible as it can save lots of time. More painful migrations will be covered in the future but this post is my favorite 'fast and easy' process.
This is a guide to taking data from a spreadsheet and easily moving that data into a MySQL database instance. The trick is the Import Wizard in MySQL Workbench that does a lot of the detail work for you. In a future post we will go into what you have to do when you are not …
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