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 …

We all know as SQL professionals that a common use of the ALTER TABLE command is that we can change a tables’ structure in a myriad number of ways. And, that’s a good thing too because chances are, you won’t always nail down the initial structure. Due to changing business or application requirements, you may even have to add additional columns that were not considered during the schema design phase. Suppose you have many tables that are structured similarly and they all need a specific column added to their already-existing design. Under certain circumstances, using the MySQL Shell in Python mode (\py), can reduce the number of manual ALTER TABLE statements you have to type. Continue reading to see examples in the MySQL Shell…

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Introduction In this article, we are going to see how we can implement an audit logging mechanism using MySQL database triggers to store the old and new row states in JSON column types. Database tables Let’s assume we have a library application that has the following two tables: The book table stores all the books that are found in our library, and the book_audit_log table stores the CDC (Change Data Capture) events that happened to a given book record via an INSERT, UPDATE, or DELETE DML statement. The book_audit_log table is created... Read More

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We all know as SQL professionals that the NULL marker is a special case. Oftentimes, you have NULL‘s stored in your tables, and that’s fine. Suppose you want to present an alternative value in query results where some of the columns have NULL? This is a perfect opportunity (but not the only) to use the IFNULL() function. I find IFNULL() quite useful when exporting query results to a CSV file or other type of flat file, providing something more meaningful than the NULL word itself. However, you only have one substitute for the NULL value when using IFNULL(), so keep that in mind. Continue reading and see examples using IFNULL() in SELECT queries…

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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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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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Have you ever had to type out a massive CREATE TABLE statement by hand? One with dozens of columns? Maybe several dozens of columns? There are likely some GUI tools to help with large CREATE TABLE commands. Or, other drag-n-drop types of software that I am not familiar with. What if you could write a few lines of Python code and take care of a huge CREATE TABLE statement with way less effort than typed manually? Interested? Continue reading and see how using pandas, pyodbc, and MySQL…

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OS, Software, and DB used:

• OpenSuse Leap 15.1
…

If you are a developer working in a MySQL environment, this blog post is for you. I share 3 MySQL commands or statements that you should know. That is a bold statement, I know. Turns out, once you do know (of) these commands, you will use them all the time. They minimize guesswork which leads to better productivity in other facets of your programming and querying workflow. I use them myself almost daily and am sure you will too once you see how simple they are to use. So why should you know them? Continue reading and find out…

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OS, Software, and DB used:

• OpenSuse Leap 15.1
…

In this post, I’ll cover examples of the MySQL TRIM() function. TRIM() removes specific characters – or spaces – from a given string, at either: the beginning, ending, or potentially in both locations depending on several factors. With an optional keyword argument that controls which character(s) – if any – are removed, TRIM() can be tricky so let’s gain understanding with several easy-to-digest examples…

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OS, Software, and DB used:

• OpenSuse Leap 15.1
• MySQL 8.0.20

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If you write MySQL queries, at some point you are going to have to provide query results in a specific order. To impose any ordering in MySQL (this applies to SQL overall and is not directed only at MySQL), you have to use the ORDER BY clause. Without it, there is no guaranteed order. The database is free to send back query results in any order. As I learn PHP, I make it a point to explore both the MySQL side, along with the PHP side in regards to similar type tasks and the efficiency of each. So far in my PHP journey, I have found that arrays are used quite extensively. In this post, I’ll cover array_multisort() – one of many in-built PHP functions – used for sorting arrays. In the context of the example data for this post, the arrays are populated by an unordered MySQL query. Let’s see one example of how you can establish a sorting order in a PHP …