MySQL SELECT and WHERE Clause Column Existence

I’m sharing another tip for anyone who wants to learn more about MySQL and how to use it. This post covers an example of the differences in columns specified in the WHERE clause but not the SELECT clause and vice-versa.

Image by Drizzt_Do_Urden from Pixabay 
The Newsletter for PHP and MySQL Developers

Receive a copy of my ebook, “10 MySQL Tips For Everyone”, absolutely free when you subscribe to the OpenLampTech newsletter.

Columns named in the WHERE clause but not the SELECT clause

Any column used as part of a WHERE clause conditional filter does not have to be listed in the SELECT column list. However, it should be present in the FROM clause named table. See the following example queries for clarity.

SELECT category_id, last_update
FROM category
WHERE name = 'Action';

You can see that the WHERE clause uses the conditional filter, name = ‘Action’, which is perfectly valid, although the SELECT statement list does not include the ‘name’ column.


📰 Get your brand, product, or service the attention it deserves with affordable classified ad placement in the OpenLampTech newsletter. I appreciate your support!


Non-existent Column in the WHERE Clause

Yet, as shown in the next example query, you cannot specify a non-existent column name in the WHERE clause conditional filter or you will get an ‘Unknown column’ error:

SELECT name, category_id, last_update
FROM category
WHERE first_name = 'Action';
Error Code: 1054. Unknown column 'first_name' in 'where clause'

On the same token, a column listed in the SELECT list that does not exist in the named FROM clause table also returns an error:

SELECT first_name, category_id, last_update
FROM category
WHERE  name = 'Action';
Error Code: 1054. Unknown column 'first_name' in 'field list'

Stay tuned for more MySQL and PHP tips and content. 🙂


Thank you for reading this post. Please share it with someone else who would enjoy it as well.


Josh Otwell has a passion to grow as a PHP Developer, SQL expert, and technical blogger/writer.

Disclaimer: The majority of examples in this post, are performed in a personal development/learning workstation environment and should not be considered production quality or ready. Your particular goals and needs may vary. Like always, just because you can do something doesn’t mean you should. My opinions are my own.

More ways I can help

Disclosure: Some of this blog post’s services and product links are affiliate links. At no additional cost to you, should you make a purchase by clicking through one of them, I will receive a commission.

The Newsletter for PHP and MySQL Developers

Receive a copy of my ebook, “10 MySQL Tips For Everyone”, absolutely free when you subscribe to the OpenLampTech newsletter.

📰 Get your brand, product, or service the attention it deserves with affordable classified ad placement in the OpenLampTech newsletter. I appreciate your support!

One thought on “MySQL SELECT and WHERE Clause Column Existence

Hey thanks for commenting! Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.