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Displaying posts with tag: Database Programming (reset)
Rolling sum and average – Window Functions MySQL

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…

Image by Steve Buissinne from …

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RANK() and DENSE_RANK() differences

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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ROW_NUMBER() Window Function – find duplicate values.

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:

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MySQL Shell get_auto_increment_value() method – Python mode

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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Use MySQL BLOB column with PHP to store .pdf file

Like always I am sharing new things I learn here on my blog. I was recently working on a requirement for a LAMP stack web application reporting dashboard in which I needed to store – and eventually – retrieve a .pdf file. I have read in several places (this fantastic book is a great resource) that a viable option is storing images or documents (.pdf in this case) in the actual database table as opposed to on the server file system. MySQL has the BLOB datatype that can be used to store files such as .pdf, .jpg, .txt, and the like. In this blog post, I cover how I accomplished uploading and storing the actual .pdf file in a BLOB column in MySQL using PHP. Any corrections, tips, pointers, and recommendations for best practices are always welcome. We all learn as we go!!!

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Use MySQL UNIQUE Constraint in phpMyAdmin

The MySQL UNIQUE constraint is often used in a column definition in which we need each value for that column to be distinct from the others. Perhaps it is an email column for an on-line registration form and we want to ensure that users cannot register twice for an account using the same email. Whatever the case may be, UNIQUE is there to help us ensure this type of data integrity or business requirement. What if the target table already exists and you determine you need to add a UNIQUE constraint to an existing column? In this post, I will cover 2 ways you can implement a UNIQUE constraint on existing columns using the phpMyAdmin web interface…

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Basic Data Analysis with MySQL Shell Python mode

I recently watched a fantastic Python Pandas library tutorial series on YouTube. Without a doubt, Pandas is great for all sorts of data stuff. On the same token, MySQL Shell in Python mode is quite powerful in the sense that Python and the MySQL Shell (version >= 8.0) are somewhat united in the same environment. Although Pandas is in a league all its own when it comes to data analysis, between the power of MySQL and Python, we can also perform some basic analysis easily in MySQL Shell Python mode. In this blog post, I will cover some basic data analysis using Python mode in the MySQL Shell. Continue reading to see examples…

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OS, Software, and DB used:

  • OpenSuse Leap …
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Use phpMyAdmin to change column name and datatype in MySQL

Using the MySQL ALTER TABLE command, you can easily change an existing columns’ name and datatype. With just a few clicks, you can do the same in the phpMyAdmin visual web interface. For many developers, this interface is the one they lean on most while programming so it can’t hurt to know how to do it yourself should you find yourself programming in this environment…

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Suppose we have a table with these 3 columns:

  • id
  • title
  • grade

Our goal is to rename the title column to paper_title and to also change the datatype …

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MySQL Shell Python mode for multiple ALTER TABLE statements – easily

There may come a time you need to rename one or more columns in an existing MySQL table for a variety of reasons. Using ALTER TABLE, to rename a column is an easy enough command. But, suppose there are multiple tables in the same database/schema that have the same-named column and all of those columns need to be renamed. That could be a lot of ALTER TABLE statements to type out. Save your energy and time, avoiding all of those ALTER TABLE commands all-together. If you are lucky enough to be working with a MySQL version > 8.0 then the Shell is your salvation. With just a few lines of Python code in \py mode, all of your trouble(s) and headache(s) are no more…

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MySQL EXTRACT() method for specific DATE and TIME values

Date and time values are some of the most important datatypes in an RDBMS. From tracking order dates to payroll hours, DATE and DATETIME datatypes are used in all types of applications. At times as a Developer, you may need only certain portions of a DATE or DATETIME value. In MySQL, the EXTRACT() function can provide you with a specific component of a DATE or DATETIME value depending on which INTERVAL is given as a parameter. Continue reading to see example EXTRACT() queries for understanding…

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